178 results on '"Wortmann SB"'
Search Results
2. Towards the genetic defect in MEGDEL syndrome: Four novel patients
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Wortmann, SB, primary, Schara, U, additional, Rodenburg, RJT, additional, de Brouwer, APM, additional, Kalkan Ucar, S, additional, Coker, M, additional, Baric, I, additional, Kluijtmans, LAJ, additional, Engelke, UFH, additional, Smeitink, JAM, additional, Wevers, RA, additional, and Morava, E, additional
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- 2010
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3. 3-Methylglutaconic aciduria type I redefined: A syndrome with late-onset leukoencephalopathy.
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Wortmann SB, Kremer BH, Graham A, Willemsen MA, Loupatty FJ, Hogg SL, Engelke UF, Kluijtmans LA, Wanders RJ, Illsinger S, Wilcken B, Cruysberg JR, Das AM, Morava E, and Wevers RA
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- 2010
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4. Biallelic C1QBP Mutations Cause Severe Neonatal-, Childhood-, or Later-Onset Cardiomyopathy Associated with Combined Respiratory-Chain Deficiencies
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Feichtinger, RG, Oláhová, M, Kishita, Y, Garone, C, Kremer, LS, Yagi, M, Uchiumi, T, Jourdain, AA, Thompson, K, D'Souza, AR, Kopajtich, R, Alston, CL, Koch, J, Sperl, W, Mastantuono, E, Strom, TM, Wortmann, SB, Meitinger, T, Pierre, G, Chinnery, PF, Chrzanowska-Lightowlers, ZM, Lightowlers, RN, DiMauro, S, Calvo, SE, Mootha, VK, Moggio, M, Sciacco, M, Comi, GP, Ronchi, D, Murayama, K, Ohtake, A, Rebelo-Guiomar, P, Kohda, M, Kang, D, Mayr, JA, Taylor, RW, Okazaki, Y, Minczuk, M, and Prokisch, H
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mitochondria ,lactate ,p32 ,PEO ,oxidative phosphorylation ,MAM33 ,multiple mtDNA deletions ,progressive external ophthalmoplegia ,3. Good health ,myopathy - Abstract
Complement component 1 Q subcomponent-binding protein (C1QBP; also known as p32) is a multi-compartmental protein whose precise function remains unknown. It is an evolutionary conserved multifunctional protein localized primarily in the mitochondrial matrix and has roles in inflammation and infection processes, mitochondrial ribosome biogenesis, and regulation of apoptosis and nuclear transcription. It has an N-terminal mitochondrial targeting peptide that is proteolytically processed after import into the mitochondrial matrix, where it forms a homotrimeric complex organized in a doughnut-shaped structure. Although C1QBP has been reported to exert pleiotropic effects on many cellular processes, we report here four individuals from unrelated families where biallelic mutations in C1QBP cause a defect in mitochondrial energy metabolism. Infants presented with cardiomyopathy accompanied by multisystemic involvement (liver, kidney, and brain), and children and adults presented with myopathy and progressive external ophthalmoplegia. Multiple mitochondrial respiratory-chain defects, associated with the accumulation of multiple deletions of mitochondrial DNA in the later-onset myopathic cases, were identified in all affected individuals. Steady-state C1QBP levels were decreased in all individuals' samples, leading to combined respiratory-chain enzyme deficiency of complexes I, III, and IV. C1qbp(-/-) mouse embryonic fibroblasts (MEFs) resembled the human disease phenotype by showing multiple defects in oxidative phosphorylation (OXPHOS). Complementation with wild-type, but not mutagenized, C1qbp restored OXPHOS protein levels and mitochondrial enzyme activities in C1qbp(-/-) MEFs. C1QBP deficiency represents an important mitochondrial disorder associated with a clinical spectrum ranging from infantile lactic acidosis to childhood (cardio)myopathy and late-onset progressive external ophthalmoplegia.
5. Genome and RNA sequencing were essential to reveal cryptic intronic variants associated to defective ATP6AP1 mRNA processing.
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Morales-Romero B, Muñoz-Pujol G, Artuch R, García-Cazorla A, O'Callaghan M, Sykut-Cegielska J, Campistol J, Moreno-Lozano PJ, Oud MM, Wevers RA, Lefeber DJ, Esteve-Codina A, Yepez VA, Gagneur J, Wortmann SB, Prokisch H, Ribes A, García-Villoria J, and Tort F
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- Humans, Male, Vacuolar Proton-Translocating ATPases genetics, Congenital Disorders of Glycosylation genetics, Congenital Disorders of Glycosylation diagnosis, Congenital Disorders of Glycosylation pathology, Mutation, Whole Genome Sequencing, Exome Sequencing, Sequence Analysis, RNA, Intellectual Disability genetics, Intellectual Disability diagnosis, Intellectual Disability pathology, Child, RNA Splicing genetics, Child, Preschool, Introns genetics, RNA, Messenger genetics
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The diagnosis of Mendelian disorders has notably advanced with integration of whole exome and genome sequencing (WES and WGS) in clinical practice. However, challenges in variant interpretation and uncovered variants by WES still leave a substantial percentage of patients undiagnosed. In this context, integrating RNA sequencing (RNA-seq) improves diagnostic workflows, particularly for WES inconclusive cases. Additionally, functional studies are often necessary to elucidate the impact of prioritized variants on gene expression and protein function. Our study focused on three unrelated male patients (P1-P3) with ATP6AP1-CDG (congenital disorder of glycosylation), presenting with intellectual disability and varying degrees of hepatopathy, glycosylation defects, and an initially inconclusive diagnosis through WES. Subsequent RNA-seq was pivotal in identifying the underlying genetic causes in P1 and P2, detecting ATP6AP1 underexpression and aberrant splicing. Molecular studies in fibroblasts confirmed these findings and identified the rare intronic variants c.289-233C > T and c.289-289G > A in P1 and P2, respectively. Trio-WGS also revealed the variant c.289-289G > A in P3, which was a de novo change in both patients. Functional assays expressing the mutant alleles in HAP1 cells demonstrated the pathogenic impact of these variants by reproducing the splicing alterations observed in patients. Our study underscores the role of RNA-seq and WGS in enhancing diagnostic rates for genetic diseases such as CDG, providing new insights into ATP6AP1-CDG molecular bases by identifying the first two deep intronic variants in this X-linked gene. Additionally, our study highlights the need to integrate RNA-seq and WGS, followed by functional validation, in routine diagnostics for a comprehensive evaluation of patients with an unidentified molecular etiology., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)
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- 2024
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6. Biallelic variants in Plexin B2 ( PLXNB2 ) cause amelogenesis imperfecta, hearing loss and intellectual disability.
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Smith CEL, Laugel-Haushalter V, Hany U, Best S, Taylor RL, Poulter JA, Wortmann SB, Feichtinger RG, Mayr JA, Al Bahlani S, Nikolopoulos G, Rigby A, Black GC, Watson CM, Mansour S, Inglehearn CF, Mighell AJ, and Bloch-Zupan A
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- Humans, Animals, Male, Female, Mice, Receptors, Cell Surface genetics, Nerve Tissue Proteins genetics, Alleles, Child, Hearing Loss genetics, Hearing Loss pathology, Hearing Loss, Sensorineural genetics, Hearing Loss, Sensorineural pathology, Adult, Mutation genetics, Adolescent, Child, Preschool, Phenotype, Intellectual Disability genetics, Intellectual Disability pathology, Pedigree, Amelogenesis Imperfecta genetics, Amelogenesis Imperfecta pathology
- Abstract
Background: Plexins are large transmembrane receptors for the semaphorin family of signalling proteins. Semaphorin-plexin signalling controls cellular interactions that are critical during development as well as in adult life stages. Nine plexin genes have been identified in humans, but despite the apparent importance of plexins in development, only biallelic PLXND1 and PLXNA1 variants have so far been associated with Mendelian genetic disease., Methods: Eight individuals from six families presented with a recessively inherited variable clinical condition, with core features of amelogenesis imperfecta (AI) and sensorineural hearing loss (SNHL), with variable intellectual disability. Probands were investigated by exome or genome sequencing. Common variants and those unlikely to affect function were excluded. Variants consistent with autosomal recessive inheritance were prioritised. Variant segregation analysis was performed by Sanger sequencing. RNA expression analysis was conducted in C57Bl6 mice., Results: Rare biallelic pathogenic variants in plexin B2 ( PLXNB2 ), a large transmembrane semaphorin receptor protein, were found to segregate with disease in all six families. The variants identified include missense, nonsense, splicing changes and a multiexon deletion. Plxnb2 expression was detected in differentiating ameloblasts., Conclusion: We identify rare biallelic pathogenic variants in PLXNB2 as a cause of a new autosomal recessive, phenotypically diverse syndrome with AI and SNHL as core features. Intellectual disability, ocular disease, ear developmental abnormalities and lymphoedema were also present in multiple cases. The variable syndromic human phenotype overlaps with that seen in Plxnb2 knockout mice, and, together with the rarity of human PLXNB2 variants, may explain why pathogenic variants in PLXNB2 have not been reported previously., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)
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- 2024
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7. The Benefit of Detecting Reduced Intracellular B12 Activity through Newborn Screening Remains Unclear.
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Knöpfli S, Goeschl B, Zeyda M, Baghdasaryan A, Baumgartner-Kaut M, Baumgartner MR, Herle M, Margreitter J, Poms M, Wortmann SB, Konstantopoulou V, and Huemer M
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Vitamin B12 (B12) deficiency (B12D) can have detrimental effects on early growth and development. The Austrian newborn screening (NBS) program targets inborn errors of cobalamin metabolism and also detects B12D. Of 59 included neonates with B12D suspected by NBS, B12D was not further investigated in 16 (27%) retrospectively identified cases, not confirmed in 28 (48%), and confirmed in 15 (25%) cases. NBS and recall biomarkers were recorded. Age at sampling of the dried blood spots for NBS and the 1st-tier methionine/phenylalanine ratio were the strongest parameters to predict B12D (67.4% correct allocations). No differences between cases with confirmed, unconfirmed, or unknown B12D or differences to norms were observed for growth and psychomotor development (Vineland III scales, phone interviews with parents of children between months 10 and 14 of life). B12 intake was below recommendations in most mothers. NBS can detect reduced intracellular B12 activity. No advantage of NBS detection and treatment regarding infant cognitive development or growth could be proven. Since conspicuous NBS findings cannot be ignored, and to prevent exposing newborns to invasive diagnostics, assessment of maternal B12 status during pregnancy seems advisable.
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- 2024
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8. Empagliflozin for treating neutropenia and neutrophil dysfunction in 21 infants with glycogen storage disease 1b.
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Grünert SC, Gautschi M, Baker J, Boyer M, Burlina A, Casswall T, Corpeleijn W, Çıki K, Cotter M, Crushell E, Derks TGJ, Haas D, Kilavuz S, Kingma SDK, Korman SH, Kozek A, de Laet C, Mundy H, Nassogne MC, Quintero V, Rossi A, Spenger J, Spiegel R, Stephenne X, Stojkov D, Tal G, Veiga-da Cunha M, and Wortmann SB
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- Humans, Male, Female, Infant, Retrospective Studies, Sodium-Glucose Transporter 2 Inhibitors therapeutic use, Treatment Outcome, Granulocyte Colony-Stimulating Factor therapeutic use, Glycogen Storage Disease Type I drug therapy, Glycogen Storage Disease Type I complications, Neutropenia drug therapy, Benzhydryl Compounds therapeutic use, Benzhydryl Compounds administration & dosage, Neutrophils drug effects, Glucosides therapeutic use, Glucosides pharmacology, Glucosides administration & dosage
- Abstract
Empagliflozin has been successfully repurposed for treating neutropenia and neutrophil dysfunction in patients with glycogen storage disease type 1b (GSD 1b), however, data in infants are missing. We report on efficacy and safety of empagliflozin in infants with GSD 1b. This is an international retrospective case series on 21 GSD 1b infants treated with empagliflozin (total treatment time 20.6 years). Before starting empagliflozin (at a median age of 8.1 months with a median dose of 0.3 mg/kg/day) 12 patients had clinical signs and symptoms of neutrophil dysfunction. Six of these previously symptomatic patients had no further neutropenia/neutrophil dysfunction-associated findings on empagliflozin. Eight patients had no signs and symptoms of neutropenia/neutrophil dysfunction before start and during empagliflozin treatment. One previously asymptomatic individual with a horseshoe kidney developed a central line infection with pyelonephritis and urosepsis during empagliflozin treatment. Of the 10 patients who were treated with G-CSF before starting empagliflozin, this was stopped in four and decreased in another four. Eleven individuals were never treated with G-CSF. While in 17 patients glucose homeostasis remained stable on empagliflozin, four showed glucose homeostasis instability in the introductory phase. In 17 patients, no other side effects were reported, while genital (n = 2) or oral (n = 1) candidiasis and skin infection (n = 1) were reported in the remaining four. Empagliflozin had a good effect on neutropenia/neutrophil dysfunction-related signs and symptoms and a favourable safety profile in infants with GSD 1b and therefore qualifies for further exploration as first line treatment., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)
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- 2024
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9. Ending an Odyssey? The Psychosocial Experiences of Parents after the Genetic Diagnosis of a Mitochondrial Disease in Children.
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Heath O, Hammerl E, Spitzinger A, and Wortmann SB
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Obtaining a genetic diagnosis of a primary mitochondrial disease (PMD) is often framed as a diagnostic odyssey. Yet, even after receiving a diagnosis, parents of affected children experience ongoing therapeutic and prognostic uncertainty and considerable psychosocial challenges. Semi-structured interviews (N = 24) were conducted with parents of 13 children (aged 2-19 years) with a genetically confirmed PMD. Paternal (N = 11) and maternal (N = 13) perspectives were obtained, and thematic analysis was performed on all interviews. A genetic diagnosis was valuable and empowering for parents, despite eliciting varied emotional responses. While the diagnosis helped focus management decisions, families often felt overwhelmed and unsupported in navigating the healthcare system. Most parents reported a serious impact on their romantic relationship. The sources of social support varied, with a preference for established friendship and family support networks over disease-specific community support groups. Most parents favored prenatal genetic testing in the event of a future pregnancy. This study provides insight into the lived experiences of parents after a genetic diagnosis of PMD in their children. The findings draw awareness to supportive care needs and highlight important gaps that should be addressed to ensure that parents feel supported within a holistic framework of management for PMDs.
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- 2024
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10. Genetic landscape of pediatric acute liver failure of indeterminate origin.
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Lenz D, Schlieben LD, Shimura M, Bianzano A, Smirnov D, Kopajtich R, Berutti R, Adam R, Aldrian D, Baric I, Baumann U, Bozbulut NE, Brugger M, Brunet T, Bufler P, Burnytė B, Calvo PL, Crushell E, Dalgiç B, Das AM, Dezsőfi A, Distelmaier F, Fichtner A, Freisinger P, Garbade SF, Gaspar H, Goujon L, Hadzic N, Hartleif S, Hegen B, Hempel M, Henning S, Hoerning A, Houwen R, Hughes J, Iorio R, Iwanicka-Pronicka K, Jankofsky M, Junge N, Kanavaki I, Kansu A, Kaspar S, Kathemann S, Kelly D, Kirsaçlioğlu CT, Knoppke B, Kohl M, Kölbel H, Kölker S, Konstantopoulou V, Krylova T, Kuloğlu Z, Kuster A, Laass MW, Lainka E, Lurz E, Mandel H, Mayerhanser K, Mayr JA, McKiernan P, McClean P, McLin V, Mention K, Müller H, Pasquier L, Pavlov M, Pechatnikova N, Peters B, Petković Ramadža D, Piekutowska-Abramczuk D, Pilic D, Rajwal S, Rock N, Roetig A, Santer R, Schenk W, Semenova N, Sokollik C, Sturm E, Taylor RW, Tschiedel E, Urbonas V, Urreizti R, Vermehren J, Vockley J, Vogel GF, Wagner M, van der Woerd W, Wortmann SB, Zakharova E, Hoffmann GF, Meitinger T, Murayama K, Staufner C, and Prokisch H
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- Child, Humans, Neoplasm Recurrence, Local, Biomarkers, Europe, Liver Failure, Acute diagnosis, Liver Transplantation adverse effects
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Background and Aims: Pediatric acute liver failure (PALF) is a life-threatening condition. In Europe, the main causes are viral infections (12%-16%) and inherited metabolic diseases (14%-28%). Yet, in up to 50% of cases the underlying etiology remains elusive, challenging clinical management, including liver transplantation. We systematically studied indeterminate PALF cases referred for genetic evaluation by whole-exome sequencing (WES), and analyzed phenotypic and biochemical markers, and the diagnostic yield of WES in this condition., Approach and Results: With this international, multicenter observational study, patients (0-18 y) with indeterminate PALF were analyzed by WES. Data on the clinical and biochemical phenotype were retrieved and systematically analyzed., Results: In total, 260 indeterminate PALF patients from 19 countries were recruited between 2011 and 2022, of whom 59 had recurrent PALF. WES established a genetic diagnosis in 37% of cases (97/260). Diagnostic yield was highest in children with PALF in the first year of life (41%), and in children with recurrent acute liver failure (64%). Thirty-six distinct disease genes were identified. Defects in NBAS (n=20), MPV17 (n=8), and DGUOK (n=7) were the most frequent findings. When categorizing, the most frequent were mitochondrial diseases (45%), disorders of vesicular trafficking (28%), and cytosolic aminoacyl-tRNA synthetase deficiencies (10%). One-third of patients had a fatal outcome. Fifty-six patients received liver transplantation., Conclusions: This study elucidates a large contribution of genetic causes in PALF of indeterminate origin with an increasing spectrum of disease entities. The high proportion of diagnosed cases and potential treatment implications argue for exome or in future rapid genome sequencing in PALF diagnostics., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)
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- 2024
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11. Clinical, Neuroimaging, and Metabolic Footprint of the Neurodevelopmental Disorder Caused by Monoallelic HK1 Variants.
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Wortmann SB, Feichtinger RG, Abela L, van Gemert LA, Aubart M, Dufeu-Berat CM, Boddaert N, de Coo R, Stühn L, Hebbink J, Heinritz W, Hildebrandt J, Himmelreich N, Korenke C, Lehman A, Leyland T, Makowski C, Martinez Marin RJ, Marzin P, Mühlhausen C, Rio M, Rotig A, Roux CJ, Schiff M, Haack TB, Syrbe S, Zylicz SA, Thiel C, Veiga da Cunha M, van Schaftingen E, Wagner M, Mayr JA, Wevers RA, Boltshauser E, and Willemsen MA
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Background and Objectives: Hexokinase 1 (encoded by HK1 ) catalyzes the first step of glycolysis, the adenosine triphosphate-dependent phosphorylation of glucose to glucose-6-phosphate. Monoallelic HK1 variants causing a neurodevelopmental disorder (NDD) have been reported in 12 individuals., Methods: We investigated clinical phenotypes, brain MRIs, and the CSF of 15 previously unpublished individuals with monoallelic HK1 variants and an NDD phenotype., Results: All individuals had recurrent variants likely causing gain-of-function, representing mutational hot spots. Eight individuals (c.1370C>T) had a developmental and epileptic encephalopathy with infantile onset and virtually no development. Of the other 7 individuals (n = 6: c.1334C>T; n = 1: c.1240G>A), 3 adults showed a biphasic course of disease with a mild static encephalopathy since early childhood and an unanticipated progressive deterioration with, e.g., movement disorder, psychiatric disease, and stroke-like episodes, epilepsy, starting in adulthood. Individuals who clinically presented in the first months of life had (near)-normal initial neuroimaging and severe cerebral atrophy during follow-up. In older children and adults, we noted progressive involvement of basal ganglia including Leigh-like MRI patterns and cerebellar atrophy, with remarkable intraindividual variability. The CSF glucose and the CSF/blood glucose ratio were below the 5th percentile of normal in almost all CSF samples, while blood glucose was unremarkable. This biomarker profile resembles glucose transporter type 1 deficiency syndrome; however, in HK1-related NDD, CSF lactate was significantly increased in all patients resulting in a substantially different biomarker profile., Discussion: Genotype-phenotype correlations appear to exist for HK1 variants and can aid in counseling. A CSF biomarker profile with low glucose, low CSF/blood glucose, and high CSF lactate may point toward monoallelic HK1 variants causing an NDD. This can help in variant interpretation and may aid in understanding the pathomechanism. We hypothesize that progressive intoxication and/or ongoing energy deficiency lead to the clinical phenotypes and progressive neuroimaging findings., Competing Interests: Several authors of this publication are members of the European Reference Network for Rare Hereditary Metabolic Disorders (MetabERN) - Project ID No 739543. Go to Neurology.org/NG for full disclosures., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)
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- 2024
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12. Response to Kulseth.
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Vogel GF, Feichtinger RG, Mayr JA, and Wortmann SB
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Competing Interests: Conflict of Interest The authors declare no conflicts of interest.
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- 2024
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13. Repurposing empagliflozin in individuals with glycogen storage disease Ib: A value-based healthcare approach and systematic benefit-risk assessment.
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Derks TGJ, Venema A, Köller C, Bos E, Overduin RJ, Stolwijk NN, Hofbauer P, Bolhuis MS, van Eenennaam F, Groen H, Hollak CEM, and Wortmann SB
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- Humans, Retrospective Studies, Risk Assessment, Value-Based Health Care, Benzhydryl Compounds, Glycogen Storage Disease Type I, Glucosides
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Off-label repurposing of empagliflozin allows pathomechanism-based treatment of neutropenia/neutrophil-dysfunction in glycogen storage disease type Ib (GSDIb). From a value-based healthcare (VBHC) perspective, we here retrospectively studied patient-reported, clinical and pharmacoeconomic outcomes in 11 GSDIb individuals before and under empagliflozin at two centers (the Netherlands [NL], Austria [AT]), including a budget impact analysis, sensitivity-analysis, and systematic benefit-risk assessment. Under empagliflozin, all GSDIb individuals reported improved quality-of-life-scores. Neutrophil dysfunction related symptoms allowed either granulocyte colony-stimulating factor cessation or tapering. Calculated cost savings per patient per year ranged between € 6482-14 190 (NL) and € 1281-41 231 (AT). The budget impact analysis estimated annual total cost savings ranging between € 75 062-225 716 (NL) and € 37 697-231 790 (AT), based on conservative assumptions. The systematic benefit-risk assessment was favorable. From a VBHC perspective, empagliflozin treatment in GSDIb improved personal and clinical outcomes while saving costs, thereby creating value at multiple pillars. We emphasize the importance to reimburse empagliflozin for GSDIb individuals, further supported by the favorable systematic benefit-risk assessment. These observations in similar directions in two countries/health care systems strongly suggest that our findings can be extrapolated to other geographical areas and health care systems., (© 2024 The Authors. Journal of Inherited Metabolic Disease published by John Wiley & Sons Ltd on behalf of SSIEM.)
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- 2024
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14. Treatment recommendations for glycogen storage disease type IB- associated neutropenia and neutrophil dysfunction with empagliflozin: Consensus from an international workshop.
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Grünert SC, Derks TGJ, Mundy H, Dalton RN, Donadieu J, Hofbauer P, Jones N, Uçar SK, LaFreniere J, Contreras EL, Pendyal S, Rossi A, Schneider B, Spiegel R, Stepien KM, Wesol-Kucharska D, Veiga-da-Cunha M, and Wortmann SB
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- Humans, Neutrophils metabolism, Consensus, Monosaccharide Transport Proteins, Antiporters metabolism, Glycogen Storage Disease Type I complications, Glycogen Storage Disease Type I drug therapy, Glycogen Storage Disease Type I genetics, Neutropenia drug therapy, Neutropenia etiology, Benzhydryl Compounds, Glucosides
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Glycogen storage disease type Ib (GSD Ib, biallelic variants in SLC37A4) is a rare disorder of glycogen metabolism complicated by neutropenia/neutrophil dysfunction. Since 2019, the SGLT2-inhibitor empagliflozin has provided a mechanism-based treatment option for the symptoms caused by neutropenia/neutrophil dysfunction (e.g. mucosal lesions, inflammatory bowel disease). Because of the rarity of GSD Ib, the published evidence on safety and efficacy of empagliflozin is still limited and does not allow to develop evidence-based guidelines. Here, an international group of experts provides 14 best practice consensus treatment recommendations based on expert practice and review of the published evidence. We recommend to start empagliflozin in all GSD Ib individuals with clinical or laboratory signs related to neutropenia/neutrophil dysfunction with a dose of 0.3-0.4 mg/kg/d given as a single dose in the morning. Treatment can be started in an outpatient setting. The dose should be adapted to the weight and in case of inadequate clinical treatment response or side effects. We strongly recommend to pause empagliflozin immediately in case of threatening dehydration and before planned longer surgeries. Discontinuation of G-CSF therapy should be attempted in all individuals. If available, 1,5-AG should be monitored. Individuals who have previously not tolerated starches should be encouraged to make a new attempt to introduce starch in their diet after initiation of empagliflozin treatment. We advise to monitor certain safety and efficacy parameters and recommend continuous, alternatively frequent glucose measurements during the introduction of empagliflozin. We provide specific recommendations for special circumstances like pregnancy and liver transplantation., Competing Interests: Declaration of competing interest All authors with exception of ELC, JlF, PH and SKU received accommodation support by Sophie's Hope Foundation. All authors report no conflict of interest related to this study. TGJD declares that he has confidentiality agreements with third parties. In the past 36 months, there have been consultation agreements (with Danone, Ultragenyx Pharmaceutical Inc, ModernaTX Inc., and Beam Therapeutics), contracts for financial research support for investigator-initiated research (NCT04311307) and sponsor-initiated research (NCT03517085, NCT03970278, NCT05139316, and NCT05196165), honoraria for lectures or presentations (by MEDTalks, Prelum, and Danone), and participations in a Data Safety Monitoring Board (NCT05095727) and Advisory Boards (Ultragenyx Pharmaceutical Inc, ModernaTX Inc., and Beam Therapeutics). For all private-public relationships, all contracts are via UMCG Contract Research Desk and all payments are to UMCG. ND declares that he is a director and minority shareholder in SpOtOn Clinical Diagnostics Ltd. KMS declares that in the last 36 months there were consultancy agreements with BioMarin, Chiesi, Takeda, Sanofi, Amicus and Immusoft Corporation. SCG declares that over the last 3 years in the area of inherited metabolic diseases she has received accommodation support from Nutricia Metabolics, honoraria for lectures from Vitaflo and Ultragenyx, and that she is an advisory board member of Ultragenyx. JL and BS declare no conflict of interest. Funding to Sophie's Hope Foundation and curegsd1b.org is by individual donors, rather than pharmaceutical or medical food industry. ELC declares no conflict of interest. C.D. Nina la Guerrera (www.ninalaguerrera.org) is a small size non-for-profit platform, whose main sources of funding are by individual donors from sectors that have no interest in biomedical research. HM declares that over the last 3 years in the area of inherited metabolic diseases she has received accommodation support from Vitaflo. honoraria for lectures from Vitaflo and Nutricia and served as a paid consultant for Ultragenyx. SBW declares that over the last 3 years in the area of inherited metabolic diseases she has received accommodation support from Nutricia Metabolics., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2024
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15. New Cases of Maleylacetoacetate Isomerase Deficiency with Detection by Newborn Screening and Natural History over 32 Years: Experience from a German Newborn Screening Center.
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Gramer G, Wortmann SB, Fang-Hoffmann J, Kohlmüller D, Okun JG, Prokisch H, Meitinger T, and Hoffmann GF
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Newborn screening (NBS) for hepatorenal tyrosinemia type I (HT1) based on a determination of succinylacetone is performed in countries worldwide. Recently, biallelic pathogenic variants in GSTZ1 underlying maleylacetoacetate isomerase (MAAI) deficiency have been described as a differential diagnosis in individuals with slightly elevated succinylacetone detected by NBS. We report the experience with NBS for HT1 over 53 months in a large German NBS center and the identification and characterization of additional cases with MAAI deficiency, including one individual with a natural history over 32 years. A total of 516,803 children underwent NBS for HT1 at the NBS center in Heidelberg between August 2016 and December 2020. Of 42 children with elevated succinylacetone, HT1 was confirmed in two cases (1 in 258.401). MAAI deficiency was suspected in two cases and genetically confirmed in one who showed traces of succinylacetone in urine. A previously unreported pathogenic GSTZ1 variant was found in the index in a biallelic state. Segregation analysis revealed monoallelic carriership in the index case's mother and homozygosity in his father. The 32-year-old father had no medical concerns up to that point and the laboratory work-up was unremarkable. MAAI has to be considered a rare differential diagnosis in NBS for HT1 in cases with slight elevations of succinylacetone to allow for correct counselling and treatment decisions. Our observation of natural history over 32 years adds evidence for a benign clinical course of MAAI deficiency without specific treatment.
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- 2024
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16. Current management of primary mitochondrial disorders in EU countries: the European Reference Networks survey.
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Mancuso M, Lopriore P, Lamperti C, Klopstock T, Rahman S, Licchetta L, Kornblum C, Wortmann SB, Dollfus H, Papadopoulou MT, Arzimanoglou A, Scarpa M, Graessner H, and Evangelista T
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- Humans, Europe, Surveys and Questionnaires, Delivery of Health Care, Mitochondrial Diseases diagnosis, Mitochondrial Diseases genetics, Mitochondrial Diseases therapy
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Background and Purpose: Primary mitochondrial diseases (PMDs) are rare diseases for which diagnosis is challenging, and management and training programs are not well defined in Europe. To capture and assess care needs, five different European Reference Networks have conducted an exploratory survey., Methods: The survey covering multiple topics relating to PMDs was sent to all ERNs healthcare providers (HCPs) in Europe., Results: We have collected answers from 220 members based in 24/27 European member states and seven non-European member states. Even though most of the responders are aware of neurogenetic diseases, difficulties arise in the ability to deliver comprehensive genetic testing. While single gene analysis is widely available in Europe, whole exome and genome sequencing are not easily accessible, with considerable variation between countries and average waiting time for results frequently above 6 months. Only 12.7% of responders were happy with the ICD-10 codes for classifying patients with PMDs discharged from the hospital, and more than 70% of them consider that PMDs deserve specific ICD codes to improve clinical management, including tailored healthcare, and for reimbursement reasons. Finally, 90% of responders declared that there is a need for further education and training in these diseases., Conclusions: This survey provides information on the current difficulties in the care of PMDs in Europe. We believe that the results of this survey are important to help rare disease stakeholders in European countries identify key care and research priorities., (© 2023. The Author(s).)
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- 2024
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17. PPA1 Deficiency Causes a Deranged Galactose Metabolism Recognizable in Neonatal Screening.
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Achleitner MT, Jans JJM, Ebner L, Spenger J, Konstantopoulou V, Feichtinger RG, Brugger K, Mayr D, Wevers RA, Thiel C, Wortmann SB, and Mayr JA
- Abstract
Two siblings showed increased galactose and galactose-related metabolites in neonatal screening. Diagnostic workup did not reveal abnormalities in any of the known disease-causing enzymes involved in galactose metabolism. Using whole-exome sequencing, we identified a homozygous missense variant in PPA1 encoding the cytosolic pyrophosphatase 1 (PPA1), c.557C>T (p.Thr186Ile). The enzyme activity of PPA1 was determined using a colorimetric assay, and the protein content was visualized via western blotting in skin fibroblasts from one of the affected individuals. The galactolytic activity of the affected fibroblasts was determined by measuring extracellular acidification with a Seahorse XFe96 analyzer. PPA1 activity decreased to 22% of that of controls in the cytosolic fraction of homogenates from patient fibroblasts. PPA1 protein content decreased by 50% according to western blot analysis, indicating a reduced stability of the variant protein. The extracellular acidification rate was reduced in patient fibroblasts when galactose was used as a substrate. Untargeted metabolomics of blood samples revealed an elevation of other metabolites related to pyrophosphate metabolism. Besides hyperbilirubinemia in the neonatal period in one child, both children were clinically unremarkable at the ages of 3 and 14 years, respectively. We hypothesize that the observed metabolic derangement is a possible mild manifestation of PPA1 deficiency. Unresolved abnormalities in galactosemia screening might result in the identification of more individuals with PPA1 deficiency, a newly discovered inborn metabolic disorder (IMD).
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- 2023
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18. SLC4A10 mutation causes a neurological disorder associated with impaired GABAergic transmission.
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Fasham J, Huebner AK, Liebmann L, Khalaf-Nazzal R, Maroofian R, Kryeziu N, Wortmann SB, Leslie JS, Ubeyratna N, Mancini GMS, van Slegtenhorst M, Wilke M, Haack TB, Shamseldin HE, Gleeson JG, Almuhaizea M, Dweikat I, Abu-Libdeh B, Daana M, Zaki MS, Wakeling MN, McGavin L, Turnpenny PD, Alkuraya FS, Houlden H, Schlattmann P, Kaila K, Crosby AH, Baple EL, and Hübner CA
- Subjects
- Child, Mice, Humans, Animals, Mutation genetics, Neurotransmitter Agents, gamma-Aminobutyric Acid genetics, Mammals metabolism, Chloride-Bicarbonate Antiporters genetics, Chloride-Bicarbonate Antiporters metabolism, Sodium-Bicarbonate Symporters genetics, Sodium-Bicarbonate Symporters metabolism, Seizures genetics
- Abstract
SLC4A10 is a plasma-membrane bound transporter that utilizes the Na+ gradient to drive cellular HCO3- uptake, thus mediating acid extrusion. In the mammalian brain, SLC4A10 is expressed in principal neurons and interneurons, as well as in epithelial cells of the choroid plexus, the organ regulating the production of CSF. Using next generation sequencing on samples from five unrelated families encompassing nine affected individuals, we show that biallelic SLC4A10 loss-of-function variants cause a clinically recognizable neurodevelopmental disorder in humans. The cardinal clinical features of the condition include hypotonia in infancy, delayed psychomotor development across all domains and intellectual impairment. Affected individuals commonly display traits associated with autistic spectrum disorder including anxiety, hyperactivity and stereotyped movements. In two cases isolated episodes of seizures were reported in the first few years of life, and a further affected child displayed bitemporal epileptogenic discharges on EEG without overt clinical seizures. While occipitofrontal circumference was reported to be normal at birth, progressive postnatal microcephaly evolved in 7 out of 10 affected individuals. Neuroradiological features included a relative preservation of brain volume compared to occipitofrontal circumference, characteristic narrow sometimes 'slit-like' lateral ventricles and corpus callosum abnormalities. Slc4a10 -/- mice, deficient for SLC4A10, also display small lateral brain ventricles and mild behavioural abnormalities including delayed habituation and alterations in the two-object novel object recognition task. Collapsed brain ventricles in both Slc4a10-/- mice and affected individuals suggest an important role of SLC4A10 in the production of the CSF. However, it is notable that despite diverse roles of the CSF in the developing and adult brain, the cortex of Slc4a10-/- mice appears grossly intact. Co-staining with synaptic markers revealed that in neurons, SLC4A10 localizes to inhibitory, but not excitatory, presynapses. These findings are supported by our functional studies, which show the release of the inhibitory neurotransmitter GABA is compromised in Slc4a10-/- mice, while the release of the excitatory neurotransmitter glutamate is preserved. Manipulation of intracellular pH partially rescues GABA release. Together our studies define a novel neurodevelopmental disorder associated with biallelic pathogenic variants in SLC4A10 and highlight the importance of further analyses of the consequences of SLC4A10 loss-of-function for brain development, synaptic transmission and network properties., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain.)
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- 2023
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19. Beyond genetics: Deciphering the impact of missense variants in CAD deficiency.
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Del Caño-Ochoa F, Ng BG, Rubio-Del-Campo A, Mahajan S, Wilson MP, Vilar M, Rymen D, Sánchez-Pintos P, Kenny J, Ley Martos M, Campos T, Wortmann SB, Freeze HH, and Ramón-Maiques S
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- Humans, Mutation, Missense, Uridine, Dihydroorotase chemistry, Dihydroorotase genetics, Dihydroorotase metabolism, Proteins
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CAD is a large, 2225 amino acid multienzymatic protein required for de novo pyrimidine biosynthesis. Pathological CAD variants cause a developmental and epileptic encephalopathy which is highly responsive to uridine supplements. CAD deficiency is difficult to diagnose because symptoms are nonspecific, there is no biomarker, and the protein has over 1000 known variants. To improve diagnosis, we assessed the pathogenicity of 20 unreported missense CAD variants using a growth complementation assay that identified 11 pathogenic variants in seven affected individuals; they would benefit from uridine treatment. We also tested nine variants previously reported as pathogenic and confirmed the damaging effect of seven. However, we reclassified two variants as likely benign based on our assay, which is consistent with their long-term follow-up with uridine. We found that several computational methods are unreliable predictors of pathogenic CAD variants, so we extended the functional assay results by studying the impact of pathogenic variants at the protein level. We focused on CAD's dihydroorotase (DHO) domain because it accumulates the largest density of damaging missense changes. The atomic-resolution structures of eight DHO pathogenic variants, combined with functional and molecular dynamics analyses, provided a comprehensive structural and functional understanding of the activity, stability, and oligomerization of CAD's DHO domain. Combining our functional and protein structural analysis can help refine clinical diagnostic workflow for CAD variants in the genomics era., (© 2023 The Authors. Journal of Inherited Metabolic Disease published by John Wiley & Sons Ltd on behalf of SSIEM.)
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- 2023
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20. Treatment of Mitochondrial Phenylalanyl-tRNa-Synthetase Deficiency (FARS2) with Oral Phenylalanine.
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Oswald SL, Steinbrücker K, Achleitner MT, Göschl E, Bittner RE, Schmidt WM, Tiefenthaler E, Hammerl E, Eisl A, Mayr D, Mayr JA, and Wortmann SB
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- Child, Female, Humans, Child, Preschool, Phenylalanine metabolism, Quality of Life, Mitochondria genetics, Mitochondria metabolism, RNA, Transfer metabolism, Mitochondrial Proteins genetics, Phenylalanine-tRNA Ligase genetics, Phenylalanine-tRNA Ligase chemistry, Phenylalanine-tRNA Ligase metabolism
- Abstract
Objective: By loading transfer RNAs with their cognate amino acids, aminoacyl-tRNA synthetases (ARS) are essential for protein translation. Both cytosolic ARS1-deficiencies and mitochondrial ARS2 deficiencies can cause severe diseases. Amino acid supplementation has shown to positively influence the clinical course of four individuals with cytosolic ARS1 deficiencies. We hypothesize that this intervention could also benefit individuals with mitochondrial ARS2 deficiencies., Methods: This study was designed as a N-of-1 trial. Daily oral L-phenylalanine supplementation was used in a 3-year-old girl with FARS2 deficiency. A period without supplementation was implemented to discriminate the effects of treatment from age-related developments and continuing physiotherapy. Treatment effects were measured through a physiotherapeutic testing battery, including movement assessment battery for children, dynamic gait index, gross motor function measure 66, and quality of life questionnaires., Results: The individual showed clear improvement in all areas tested, especially in gross motor skills, movement abilities, and postural stability. In the period without supplementation, she lost newly acquired motor skills but regained these upon restarting supplementation. No adverse effects and good tolerance of treatment were observed., Interpretation and Conclusion: Our positive results encourage further studies both on L-phenylalanine for other individuals with FARS2 deficiency and the exploration of this treatment rationale for other ARS2 deficiencies. Additionally, treatment costs were relatively low at 1.10 €/day., Competing Interests: None declared., (Thieme. All rights reserved.)
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- 2023
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21. KCNT2-Related Disorders: Phenotypes, Functional, and Pharmacological Properties.
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Cioclu MC, Mosca I, Ambrosino P, Puzo D, Bayat A, Wortmann SB, Koch J, Strehlow V, Shirai K, Matsumoto N, Sanders SJ, Michaud V, Legendre M, Riva A, Striano P, Muhle H, Pendziwiat M, Lesca G, Mangano GD, Nardello R, Lemke JR, Møller RS, Soldovieri MV, Rubboli G, and Taglialatela M
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- Humans, HEK293 Cells, Phenotype, Genotype, Potassium Channels, Sodium-Activated genetics, Neuroblastoma, Intellectual Disability drug therapy, Intellectual Disability genetics
- Abstract
Objective: Pathogenic variants in KCNT2 are rare causes of developmental epileptic encephalopathy (DEE). We herein describe the phenotypic and genetic features of patients with KCNT2-related DEE, and the in vitro functional and pharmacological properties of KCNT2 channels carrying 14 novel or previously untested variants., Methods: Twenty-five patients harboring KCNT2 variants were investigated: 12 were identified through an international collaborative network, 13 were retrieved from the literature. Clinical data were collected and included in a standardized phenotyping sheet. Novel variants were detected using exome sequencing and classified using ACMG criteria. Functional and pharmacological studies were performed by whole-cell electrophysiology in HEK-293 and SH-SY5Y cells., Results: The phenotypic spectrum encompassed: (a) intellectual disability/developmental delay (21/22 individuals with available information), ranging from mild to severe/profound; (b) epilepsy (15/25); (c) neurological impairment, with altered muscle tone (14/22); (d) dysmorphisms (13/20). Nineteen pathogenic KCNT2 variants were found (9 new, 10 reported previously): 16 missense, 1 in-frame deletion of a single amino acid, 1 nonsense, and 1 frameshift. Among tested variants, 8 showed gain-of-function (GoF), and 6 loss-of-function (LoF) features when expressed heterologously in vitro. Quinidine and fluoxetine blocked all GoF variants, whereas loxapine and riluzole activated some LoF variants while blocking others., Interpretation: We expanded the phenotypic and genotypic spectrum of KCNT2-related disorders, highlighting novel genotype-phenotype associations. Pathogenic KCNT2 variants cause GoF or LoF in vitro phenotypes, and each shows a unique pharmacological profile, suggesting the need for in vitro functional and pharmacological investigation to enable targeted therapies based on the molecular phenotype. ANN NEUROL 2023;94:332-349., (© 2023 American Neurological Association.)
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- 2023
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22. Investigating the role of ASCC1 in the causation of bone fragility.
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Voraberger B, Mayr JA, Fratzl-Zelman N, Blouin S, Uday S, Kopajtich R, Koedam M, Hödlmayr H, Wortmann SB, Csillag B, Prokisch H, van der Eerden BCJ, El-Gazzar A, and Högler W
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- Infant, Humans, Female, Homozygote, Sequence Deletion, Cell Differentiation, Carrier Proteins genetics, Adipogenesis, Proteins genetics
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Bi-allelic variants in ASCC1 cause the ultrarare bone fragility disorder "spinal muscular atrophy with congenital bone fractures-2" (SMABF2). However, the mechanism by which ASCC1 dysfunction leads to this musculoskeletal condition and the nature of the associated bone defect are poorly understood. By exome sequencing, we identified a novel homozygous deletion in ASCC1 in a female infant. She was born with severe muscular hypotonia, inability to breathe and swallow, and virtual absence of spontaneous movements; showed progressive brain atrophy, gracile long bones, very slender ribs, and a femur fracture; and died from respiratory failure aged 3 months. A transiliac bone sample taken postmortem revealed a distinct microstructural bone phenotype with low trabecular bone volume, low bone remodeling, disordered collagen organization, and an abnormally high bone marrow adiposity. Proteomics, RNA sequencing, and qPCR in patient-derived skin fibroblasts confirmed that ASCC1 was hardly expressed on protein and RNA levels compared with healthy controls. Furthermore, we demonstrate that mutated ASCC1 is associated with a downregulation of RUNX2 , the master regulator of osteoblastogenesis, and SERPINF1 , which is involved in osteoblast and adipocyte differentiation. It also exerts an inhibitory effect on TGF-β/SMAD signaling, which is important for bone development. Additionally, knockdown of ASCC1 in human mesenchymal stromal cells (hMSCs) suppressed their differentiation capacity into osteoblasts while increasing their differentiation into adipocytes. This resulted in reduced mineralization and elevated formation of lipid droplets. These findings shed light onto the pathophysiologic mechanisms underlying SMABF2 and assign a new biological role to ASCC1 acting as an important pro-osteoblastogenic and anti-adipogenic regulator., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Voraberger, Mayr, Fratzl-Zelman, Blouin, Uday, Kopajtich, Koedam, Hödlmayr, Wortmann, Csillag, Prokisch, van der Eerden, El-Gazzar and Högler.)
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- 2023
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23. Case Report-An Inherited Loss-of-Function NRXN3 Variant Potentially Causes a Neurodevelopmental Disorder with Autism Consistent with Previously Described 14q24.3-31.1 Deletions.
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Feichtinger RG, Preisel M, Brugger K, Wortmann SB, and Mayr JA
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- Female, Humans, Causality, Phenotype, Protein Isoforms genetics, Child, Preschool, Autism Spectrum Disorder genetics, Autistic Disorder genetics, Neurodevelopmental Disorders genetics
- Abstract
Background: Heterozygous, large-scale deletions at 14q24.3-31.1 affecting the neurexin-3 gene have been associated with neurodevelopmental disorders such as autism. Both "de novo" occurrences and inheritance from a healthy parent suggest incomplete penetrance and expressivity, especially in autism spectrum disorder. NRXN3 encodes neurexin-3, a neuronal cell surface protein involved in cell recognition and adhesion, as well as mediating intracellular signaling. NRXN3 is expressed in two distinct isoforms (alpha and beta) generated by alternative promoters and splicing. MM/Results: Using exome sequencing, we identified a monoallelic frameshift variant c.159_160del (p.Gln54AlafsTer50) in the NRXN3 beta isoform (NM_001272020.2) in a 5-year-old girl with developmental delay, autism spectrum disorder, and behavioral issues. This variant was inherited from her mother, who did not have any medical complaints., Discussion: This is the first detailed report of a loss-of-function variant in NRXN3 causing an identical phenotype, as reported for heterozygous large-scale deletions in the same genomic region, thereby confirming NRXN3 as a novel gene for neurodevelopmental disorders with autism.
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- 2023
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24. Treatment of the Neutropenia Associated with GSD1b and G6PC3 Deficiency with SGLT2 Inhibitors.
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Veiga-da-Cunha M, Wortmann SB, Grünert SC, and Van Schaftingen E
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Glycogen storage disease type Ib (GSD1b) is due to a defect in the glucose-6-phosphate transporter (G6PT) of the endoplasmic reticulum, which is encoded by the SLC37A4 gene. This transporter allows the glucose-6-phosphate that is made in the cytosol to cross the endoplasmic reticulum (ER) membrane and be hydrolyzed by glucose-6-phosphatase (G6PC1), a membrane enzyme whose catalytic site faces the lumen of the ER. Logically, G6PT deficiency causes the same metabolic symptoms (hepatorenal glycogenosis, lactic acidosis, hypoglycemia) as deficiency in G6PC1 (GSD1a). Unlike GSD1a, GSD1b is accompanied by low neutrophil counts and impaired neutrophil function, which is also observed, independently of any metabolic problem, in G6PC3 deficiency. Neutrophil dysfunction is, in both diseases, due to the accumulation of 1,5-anhydroglucitol-6-phosphate (1,5-AG6P), a potent inhibitor of hexokinases, which is slowly formed in the cells from 1,5-anhydroglucitol (1,5-AG), a glucose analog that is normally present in blood. Healthy neutrophils prevent the accumulation of 1,5-AG6P due to its hydrolysis by G6PC3 following transport into the ER by G6PT. An understanding of this mechanism has led to a treatment aimed at lowering the concentration of 1,5-AG in blood by treating patients with inhibitors of SGLT2, which inhibits renal glucose reabsorption. The enhanced urinary excretion of glucose inhibits the 1,5-AG transporter, SGLT5, causing a substantial decrease in the concentration of this polyol in blood, an increase in neutrophil counts and function and a remarkable improvement in neutropenia-associated clinical signs and symptoms.
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- 2023
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25. Patient-reported outcomes on empagliflozin treatment in glycogen storage disease type Ib: An international questionnaire study.
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Grünert SC, Venema A, LaFreniere J, Schneider B, Contreras E, Wortmann SB, and Derks TGJ
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In patients with glycogen storage disease type Ib (GSD Ib), quality of life is severely hampered by neutropenia and neutropenia-associated symptoms. SGLT2 inhibitors are a new treatment option and have shown improved medical outcomes in more than 120 patients so far. The aim of this international questionnaire study was to assess patient-reported outcomes of this new treatment in GSD Ib patients. Patients and caregivers of pediatric patients were invited to complete a web-based questionnaire. This was designed to evaluate treatment effects of the SGLT2 inhibitor empagliflozin on clinical symptoms and important aspects of daily life including physical performance, sleep, social and work life, traveling, socioeconomic aspects, and quality of life. The questionnaire was completed by 73 respondents from 17 different countries. The mean duration of treatment was 15 months, the cumulative treatment time was 94.8 years. More than 80% of patients reported an improved quality of life. The number of hospitalizations was reduced (66% of patients), as well as the number of days absent from school or work. Granulocyte colony-stimulating factor (G-CSF) treatment could be stopped in 49% of patients and reduced in another 42%. Clear improvement of neutropenia and all neutropenia-associated symptoms was reported by the majority of patients. Additionally, patients or caregivers reported positive effects on appetite (63%), level of activity (75%), overall well-being (96%), and sleep (63%). Empagliflozin positively impacts many aspects of daily life including work and social life and thereby significantly improves quality of life of patients and caregivers., Competing Interests: The authors declare that they have no competing interests concerning the content of this manuscript., (© 2023 The Authors. JIMD Reports published by John Wiley & Sons Ltd on behalf of SSIEM.)
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- 2023
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26. MOGS-CDG: Quantitative analysis of the diagnostic Glc 3 Man tetrasaccharide and clinical spectrum of six new cases.
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Post MA, de Wit I, Zijlstra FSM, Engelke UFH, van Rooij A, Christodoulou J, Tan TY, Le Fevre A, Jin D, Yaplito-Lee J, Lee BH, Low KJ, Mallick AA, Õunap K, Pitt J, Reardon W, Vals MA, Wortmann SB, Wessels HJCT, Bärenfänger M, van Karnebeek CDM, and Lefeber DJ
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- Humans, Mass Spectrometry methods, Oligosaccharides metabolism, Polysaccharides, Seizures, Congenital Disorders of Glycosylation genetics
- Abstract
Congenital disorders of glycosylation (CDG) are a clinically and biochemically heterogeneous subgroup of inherited metabolic disorders. Most CDG with abnormal N-glycosylation can be detected by transferrin screening, however, MOGS-CDG escapes this routine screening. Combined with the clinical heterogeneity of reported cases, diagnosing MOGS-CDG can be challenging. Here, we clinically characterize ten MOGS-CDG cases including six previously unreported individuals, showing a phenotype characterized by dysmorphic features, global developmental delay, muscular hypotonia, and seizures in all patients and in a minority vision problems and hypogammaglobulinemia. Glycomics confirmed accumulation of a Glc
3 Man7 GlcNAc2 glycan in plasma. For quantification of the diagnostic Glcα1-3Glcα1-3Glcα1-2Man tetrasaccharide in urine, we developed and validated a liquid chromatography-mass spectrometry method of 2-aminobenzoic acid (2AA) labeled urinary glycans. As an internal standard, isotopically labeled13 C6 -2AA Glc3 Man was used, while labeling efficiency was controlled by use of12 C6 -2AA and13 C6 -2AA labeled laminaritetraose. Recovery, linearity, intra- and interassay coefficients of variability of these labeled compounds were determined. Furthermore, Glc3 Man was specifically identified by retention time matching against authentic MOGS-CDG urine and compared with Pompe urine. Glc3 Man was increased in all six analyzed cases, ranging from 34.1 to 618.0 μmol/mmol creatinine (reference <5 μmol). In short, MOGS-CDG has a broad manifestation of symptoms but can be diagnosed with the use of a quantitative method for analysis of urinary Glc3 Man excretion., (© 2023 The Authors. Journal of Inherited Metabolic Disease published by John Wiley & Sons Ltd on behalf of SSIEM.)- Published
- 2023
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27. Nicotinamide Riboside for Ataxia Telangiectasia: A Report of an Early Treated Individual.
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Steinbrücker K, Tiefenthaler E, Schernthaner EM, Jungwirth J, and Wortmann SB
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- Humans, Adolescent, Child, Preschool, Niacinamide therapeutic use, Pyridinium Compounds, Ataxia, Ataxia Telangiectasia drug therapy
- Abstract
A first study on nicotinamide riboside treatment of 24 individuals with ataxia telangiectasia with a mean age of 17.5 years showed improved ataxia scores and immunoglobulin levels. We here present the effect of nicotinamide riboside in another individual with ataxia and recurrent infections in whom treatment started as early as at the age of 3 years and 6 months.During 11 months of follow-up, mean total Scale-for-the-Assessment-and-Rating-of-Ataxia decreased from 27 to 9 points and mean total Score for the Gross-Motor-Function-Measure increased from 61 to 78%. Improvement in drawing skills was observed by ICF-based ergotherapeutic examination. Use of antibiotics and frequency of hospitalizations due to infections were reduced by more than 90%. Immunological parameters in blood remained unchanged. No adverse effects occurred.While the effects on motor and speech improvement might be partly explained by development, our study replicates the previous finding of a positive effect of nicotinamide riboside treatment in ataxia telangiectasia. One could even hypothesize that the early treatment will lead to even better outcome. Given the absence of adverse effects, we strongly encourage to consider nicotinamide riboside in all individuals with ataxia telangiectasia., Competing Interests: None declared., (Thieme. All rights reserved.)
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- 2023
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28. The clinical and molecular landscape of congenital myasthenic syndromes in Austria: a nationwide study.
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Krenn M, Sener M, Rath J, Zulehner G, Keritam O, Wagner M, Laccone F, Iglseder S, Marte S, Baumgartner M, Eisenkölbl A, Liechtenstein C, Rudnik S, Quasthoff S, Grinzinger S, Spenger J, Wortmann SB, Löscher WN, Zimprich F, Kellersmann A, Rappold M, Bernert G, Freilinger M, and Cetin H
- Subjects
- Humans, Austria epidemiology, Acetylcholinesterase genetics, Treatment Outcome, Prevalence, Mutation, Myasthenic Syndromes, Congenital diagnosis, Myasthenic Syndromes, Congenital epidemiology, Myasthenic Syndromes, Congenital genetics
- Abstract
Background: Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders caused by genetic defects resulting in impaired neuromuscular transmission. Although effective treatments are available, CMS is probably underdiagnosed, and systematic clinico-genetic investigations are warranted., Methods: We used a nationwide approach to collect Austrian patients with genetically confirmed CMS. We provide a clinical and molecular characterization of this cohort and aimed to ascertain the current frequency of CMS in Austria., Results: Twenty-eight cases with genetically confirmed CMS were identified, corresponding to an overall prevalence of 3.1 per million (95% CI 2.0-4.3) in Austria. The most frequent genetic etiology was CHRNE (n = 13), accounting for 46.4% of the cohort. Within this subgroup, the variant c.1327del, p.(Glu443Lysfs*64) was detected in nine individuals. Moreover, causative variants were found in DOK7 (n = 4), RAPSN (n = 3), COLQ (n = 2), GMPPB (n = 2), CHAT (n = 1), COL13A1 (n = 1), MUSK (n = 1) and AGRN (n = 1). Clinical onset within the first year of life was reported in one half of the patients. Across all subtypes, the most common symptoms were ptosis (85.7%), lower limb (67.9%), upper limb (60.7%) and facial weakness (60.7%). The majority of patients (96.4%) received specific treatment, including acetylcholinesterase inhibitors in 20, adrenergic agonists in 11 and 3,4-diaminopyridine in nine patients., Conclusions: Our study presents the first systematic characterization of individuals with CMS in Austria, providing prevalence estimates and genotype-phenotype correlations that may help to improve the diagnostic approach and patient management., (© 2022. The Author(s).)
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- 2023
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29. A case report: New-onset refractory status epilepticus in a patient with FASTKD2 -related mitochondrial disease.
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Astner-Rohracher A, Mauritz M, Leitinger M, Rossini F, Kalss G, Neuray C, Retter E, Wortmann SB, Achleitner MT, Mayr JA, and Trinka E
- Abstract
Objectives: New-onset refractory status epilepticus (NORSE) is associated with high morbidity and mortality. Despite extensive work-up, the underlying etiology remains unknown in 50% of affected individuals. Mitochondrial disorders represent rare causes of NORSE. Biallelic variants in FASTKD2 were reported as a cause of infantile encephalomyopathy with refractory epilepsy., Case Description: In the study, we report a previously healthy 14-year-old with a new, homozygous FASTKD2 variant presenting with NORSE. Following a seizure-free period of 7 years, he experienced another super-refractory SE and subsequently developed drug-resistant focal epilepsy, mild myopathy, optic atrophy, and discrete psychomotor slowing. Structural MRI at the time of NORSE showed right temporo-parieto-occipital FLAIR hyperintensity and diffusion restriction, with extensive right hemispheric atrophy at the age of 22 years. Whole-exome sequencing revealed a novel homozygous loss of function variant [c.(1072C>T);(1072C>T)] [p.(Arg358Ter);(Arg358Ter)] in FASTKD2 (NM_001136193), resulting in a premature termination codon in the protein-coding region and loss of function of FASTKD2. Oxidative phosphorylation (OXPHOS) in muscle and skin fibroblasts was unremarkable., Conclusion: This is the first case of a normally developed adolescent with a new homozygous loss of function variant in FASTKD2 , manifesting with NORSE. The phenotypical spectrum of FASTKD2-related mitochondrial disease is heterogeneous, ranging from recurrent status epilepticus and refractory focal epilepsy in an adolescent with normal cognitive development to severe forms of infantile mitochondrial encephalopathy. Although mitochondrial diseases are rare causes of NORSE, clinical features such as young age at onset and multi-system involvement should trigger genetic testing. Early diagnosis is essential for counseling and treatment considerations., Competing Interests: AA-R reports travel support and speaker's honoraria from Eisai, outside the submitted work. ML reports a travel grant from UCB Pharma and a speaker's honorarium from Eisai, outside the submitted work. GK reports travel support from UCB, Eisai and Cyberonics and speaker's honoraria from Eisai, outside the submitted work. CN reports consulting honorarium from Epilog NV, outside the submitted work. ET reports personal fees from EVER Pharma, Marinus, Argenx, Arvelle/Angelini, Epilog, Medtronic, MedScape, Bial–Portela & Cª, NewBridge, GL Pharma, GlaxoSmithKline, Hikma, Boehringer Ingelheim, LivaNova, Eisai, UCB, Biogen, Genzyme Sanofi, GW Pharmaceuticals/Jazz, and Actavis outside the submitted work; his institution has received grants from Biogen, UCB Pharma, Eisai, Red Bull, Merck, Bayer, the European Union, FWF Osterreichischer Fond zur Wissenschaftsforderung, Bundesministerium fur Wissenschaft und Forschung, and Jubilaumsfond der Österreichischen Nationalbank outside the submitted work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Astner-Rohracher, Mauritz, Leitinger, Rossini, Kalss, Neuray, Retter, Wortmann, Achleitner, Mayr and Trinka.)
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- 2023
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30. Mitochondrial Disease and Hearing Loss in Children: A Systematic Review.
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Roesch S, O'Sullivan A, Zimmermann G, Mair A, Lipuš C, Mayr JA, Wortmann SB, and Rasp G
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- Humans, Hearing Loss diagnosis, Deafness, Hearing Loss, Sensorineural, Mitochondrial Diseases complications
- Abstract
Objectives: Hearing loss is a clinical symptom, frequently mentioned in the context of mitochondrial disease. With no cure available for mitochondrial disease, supportive treatment of clinical symptoms like hearing loss is of the utmost importance. The aim of this study was to summarize current knowledge on hearing loss in genetically proven mitochondrial disease in children and deduce possible and necessary consequences in patient care., Methods: Systematic literature review, including Medline, Embase, and Cochrane library. Review protocol was established and registered prior to conduction (International prospective register of systematic reviews-PROSPERO: CRD42020165356). Conduction of this review was done in accordance with MOOSE criteria., Results: A total of 23 articles, meeting predefined criteria and providing sufficient information on 75 individuals with childhood onset hearing loss was included for analysis. Both cochlear and retro-cochlear origin of hearing loss can be identified among different types of mitochondrial disease. Analysis was hindered by inhomogeneous reporting and methodical limitations., Conclusion: Overall, the findings do not allow for a general statement on hearing loss in children with mitochondrial disease. Retro-cochlear hearing loss seems to be found more often than expected. A common feature appears to be progression of hearing loss over time. However, hearing loss in these patients shows manifold characteristics. Therefore, awareness of mitochondrial disease as a possible causative background is important for otolaryngologists. Future attempts rely on standardized reporting and long-term follow-up., Level of Evidence: NA Laryngoscope, 132:2459-2472, 2022., (© 2022 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)
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- 2022
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31. Premature Ovarian Insufficiency in CLPB Deficiency: Transcriptomic, Proteomic and Phenotypic Insights.
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Tucker EJ, Baker MJ, Hock DH, Warren JT, Jaillard S, Bell KM, Sreenivasan R, Bakhshalizadeh S, Hanna CA, Caruana NJ, Wortmann SB, Rahman S, Pitceathly RDS, Donadieu J, Alimi A, Launay V, Coppo P, Christin-Maitre S, Robevska G, van den Bergen J, Kline BL, Ayers KL, Stewart PN, Stroud DA, Stojanovski D, and Sinclair AH
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- Female, Humans, Endopeptidase Clp genetics, Endopeptidase Clp metabolism, Transcriptome, Proteomics, Phenotype, Primary Ovarian Insufficiency genetics, Menopause, Premature, Cataract genetics, Neutropenia
- Abstract
Context: Premature ovarian insufficiency (POI) is a common form of female infertility that usually presents as an isolated condition but can be part of various genetic syndromes. Early diagnosis and treatment of POI can minimize comorbidity and improve health outcomes., Objective: We aimed to determine the genetic cause of syndromic POI, intellectual disability, neutropenia, and cataracts., Methods: We performed whole-exome sequencing (WES) followed by functional validation via RT-PCR, RNAseq, and quantitative proteomics, as well as clinical update of previously reported patients with variants in the caseinolytic peptidase B (CLPB) gene., Results: We identified causative variants in CLPB, encoding a mitochondrial disaggregase. Variants in this gene are known to cause an autosomal recessive syndrome involving 3-methylglutaconic aciduria, neurological dysfunction, cataracts, and neutropenia that is often fatal in childhood; however, there is likely a reporting bias toward severe cases. Using RNAseq and quantitative proteomics we validated causation and gained insight into genotype:phenotype correlation. Clinical follow-up of patients with CLPB deficiency who survived to adulthood identified POI and infertility as a common postpubertal ailment., Conclusion: A novel splicing variant is associated with CLPB deficiency in an individual who survived to adulthood. POI is a common feature of postpubertal female individuals with CLPB deficiency. Patients with CLPB deficiency should be referred to pediatric gynecologists/endocrinologists for prompt POI diagnosis and hormone replacement therapy to minimize associated comorbidities., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society.)
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- 2022
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32. A TSHZ3 Frame-Shift Variant Causes Neurodevelopmental and Renal Disorder Consistent with Previously Described Proximal Chromosome 19q13.11 Deletion Syndrome.
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Feichtinger RG, Preisel M, Steinbrücker K, Brugger K, Radda A, Wortmann SB, and Mayr JA
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- Female, Humans, Mice, Animals, Child, Transcription Factors genetics, Homeodomain Proteins genetics, Intellectual Disability genetics, Vesico-Ureteral Reflux, Kidney Diseases
- Abstract
Heterozygous deletions at 19q12-q13.11 affecting TSHZ3, the teashirt zinc finger homeobox 3, have been associated with intellectual disability and behavioural issues, congenital anomalies of the kidney and urinary tract (CAKUT), and postnatal growth retardation in humans and mice. TSHZ3 encodes a transcription factor regulating the development of neurons but is ubiquitously expressed. Using exome sequencing, we identified a heterozygous frameshift variant c.119_120dup p.Pro41SerfsTer79 in TSHZ3 in a 7-year-old girl with intellectual disability, behavioural issues, pyelocaliceal dilatation, and mild urethral stenosis. The variant was present on the paternal TSHZ3 allele. The DNA from the father was not available for testing. This is the first report of a heterozygous point mutation in TSHZ3 causing the same phenotype as reported for monoallelic deletions in the same region. This confirms TSHZ3 as a novel disease gene for neurodevelopmental disorder in combination with behavioural issues and CAKUT.
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- 2022
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33. Mitochondrial diseases mimicking autoimmune diseases of the CNS and good response to steroids initially.
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Della Marina A, Bertolini A, Wegener-Panzer A, Flotats-Bastardas M, Reinhardt T, El Naggar I, Distelmaier F, Blaschek A, Schara-Schmidt U, Brunet T, Wagner M, Smirnov D, Prokisch H, Wortmann SB, and Rostasy K
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- Child, Humans, Retrospective Studies, Recurrence, Steroids, Lactates, Autoimmune Diseases, Mitochondrial Diseases diagnosis, Mitochondrial Diseases drug therapy
- Abstract
Introduction: Neuroimmunological diseases such as autoimmune encephalitis (AE) or acquired demyelinating syndromes (ADS), can present with neurological symptoms and imaging features that are indistinguishable from mitochondrial diseases (MD) in particular at initial presentation., Methods: Retrospective analysis of the clinical, laboratory and neuroimaging features of five patients who presented with signs of a neuroimmunological disease but all had pathological pathogenic variants in genes related to mitochondrial energy metabolism., Results: Four patients presented with an acute neurological episode reminiscent of a possible AE and one patient with a suspected ADS at initial presentation. MRI findings were compatible with neuroimmunological diseases in all patients. In two children cerebrospinal fluid (CSF) studies revealed a mildly elevated cell count, two had elevated CSF lactate, none had oligoclonal bands (OCBs). All patients improved rapidly with intravenous steroids or immunoglobulins. Four patients had one or more relapses. Three patients showed worsening of their neurological symptoms with subsequent episodes and one patient died. Relapses in conjunction with new and progressive neurological symptoms, led to additional work-up which finally resulted in different genetic diagnosis of MD in all patients (MT-TL1, MT-ND5, APOA1-BP, HPDL, POLG)., Discussion: We would like to draw attention to a subset of patients with MD initially presenting with signs and symptoms mimicking neuroimmunological. Absence of CSF pleocytosis, elevated CSF lactate and progressive, relapsing course should trigger further (genetic) investigations in search of a MD even in patients with good response initially to immunomodulating therapies., Competing Interests: Declaration of competing interest A. Blaschek, Wegener-Panzer, A. Della-Marina, M. Flotats-Bastardas, T. Reinhardt, I. El Naggar, F Distelmaier, U. Schara-Schmidt, S. Wortmann, Theresa Brunet, Matia Wagner, Dimitri Smirnov, Holger Prokisch have no disclosures. K. Rostásy received speaker's honoraria from Merck and served on the advisory board of the PARADIGM study., (© 2022 Published by Elsevier Ltd on behalf of European Paediatric Neurology Society.)
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- 2022
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34. Bi-allelic LETM1 variants perturb mitochondrial ion homeostasis leading to a clinical spectrum with predominant nervous system involvement.
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Kaiyrzhanov R, Mohammed SEM, Maroofian R, Husain RA, Catania A, Torraco A, Alahmad A, Dutra-Clarke M, Grønborg S, Sudarsanam A, Vogt J, Arrigoni F, Baptista J, Haider S, Feichtinger RG, Bernardi P, Zulian A, Gusic M, Efthymiou S, Bai R, Bibi F, Horga A, Martinez-Agosto JA, Lam A, Manole A, Rodriguez DP, Durigon R, Pyle A, Albash B, Dionisi-Vici C, Murphy D, Martinelli D, Bugiardini E, Allis K, Lamperti C, Reipert S, Risom L, Laugwitz L, Di Nottia M, McFarland R, Vilarinho L, Hanna M, Prokisch H, Mayr JA, Bertini ES, Ghezzi D, Østergaard E, Wortmann SB, Carrozzo R, Haack TB, Taylor RW, Spinazzola A, Nowikovsky K, and Houlden H
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- Homeostasis genetics, Humans, Membrane Proteins genetics, Mitochondria genetics, Mitochondria metabolism, Mitochondrial Proteins genetics, Mitochondrial Proteins metabolism, Nervous System metabolism, Saccharomyces cerevisiae metabolism, Calcium-Binding Proteins genetics, Mitochondrial Diseases genetics, Mitochondrial Diseases metabolism
- Abstract
Leucine zipper-EF-hand containing transmembrane protein 1 (LETM1) encodes an inner mitochondrial membrane protein with an osmoregulatory function controlling mitochondrial volume and ion homeostasis. The putative association of LETM1 with a human disease was initially suggested in Wolf-Hirschhorn syndrome, a disorder that results from de novo monoallelic deletion of chromosome 4p16.3, a region encompassing LETM1. Utilizing exome sequencing and international gene-matching efforts, we have identified 18 affected individuals from 11 unrelated families harboring ultra-rare bi-allelic missense and loss-of-function LETM1 variants and clinical presentations highly suggestive of mitochondrial disease. These manifested as a spectrum of predominantly infantile-onset (14/18, 78%) and variably progressive neurological, metabolic, and dysmorphic symptoms, plus multiple organ dysfunction associated with neurodegeneration. The common features included respiratory chain complex deficiencies (100%), global developmental delay (94%), optic atrophy (83%), sensorineural hearing loss (78%), and cerebellar ataxia (78%) followed by epilepsy (67%), spasticity (53%), and myopathy (50%). Other features included bilateral cataracts (42%), cardiomyopathy (36%), and diabetes (27%). To better understand the pathogenic mechanism of the identified LETM1 variants, we performed biochemical and morphological studies on mitochondrial K
+ /H+ exchange activity, proteins, and shape in proband-derived fibroblasts and muscles and in Saccharomyces cerevisiae, which is an important model organism for mitochondrial osmotic regulation. Our results demonstrate that bi-allelic LETM1 variants are associated with defective mitochondrial K+ efflux, swollen mitochondrial matrix structures, and loss of important mitochondrial oxidative phosphorylation protein components, thus highlighting the implication of perturbed mitochondrial osmoregulation caused by LETM1 variants in neurological and mitochondrial pathologies., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2022
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35. Ketogenic Diet Treatment of Defects in the Mitochondrial Malate Aspartate Shuttle and Pyruvate Carrier.
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Bölsterli BK, Boltshauser E, Palmieri L, Spenger J, Brunner-Krainz M, Distelmaier F, Freisinger P, Geis T, Gropman AL, Häberle J, Hentschel J, Jeandidier B, Karall D, Keren B, Klabunde-Cherwon A, Konstantopoulou V, Kottke R, Lasorsa FM, Makowski C, Mignot C, O'Gorman Tuura R, Porcelli V, Santer R, Sen K, Steinbrücker K, Syrbe S, Wagner M, Ziegler A, Zöggeler T, Mayr JA, Prokisch H, and Wortmann SB
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- Aspartic Acid metabolism, Carbohydrates, Humans, Malates, Mitochondrial Membrane Transport Proteins genetics, Mitochondrial Membrane Transport Proteins metabolism, Monocarboxylic Acid Transporters, Citrullinemia, Diet, Ketogenic
- Abstract
The mitochondrial malate aspartate shuttle system (MAS) maintains the cytosolic NAD+/NADH redox balance, thereby sustaining cytosolic redox-dependent pathways, such as glycolysis and serine biosynthesis. Human disease has been associated with defects in four MAS-proteins (encoded by MDH1 , MDH2 , GOT2 , SLC25A12 ) sharing a neurological/epileptic phenotype, as well as citrin deficiency ( SLC25A13 ) with a complex hepatopathic-neuropsychiatric phenotype. Ketogenic diets (KD) are high-fat/low-carbohydrate diets, which decrease glycolysis thus bypassing the mentioned defects. The same holds for mitochondrial pyruvate carrier (MPC) 1 deficiency, which also presents neurological deficits. We here describe 40 (18 previously unreported) subjects with MAS-/MPC1-defects (32 neurological phenotypes, eight citrin deficiency), describe and discuss their phenotypes and genotypes (presenting 12 novel variants), and the efficacy of KD. Of 13 MAS/MPC1-individuals with a neurological phenotype treated with KD, 11 experienced benefits-mainly a striking effect against seizures. Two individuals with citrin deficiency deceased before the correct diagnosis was established, presumably due to high-carbohydrate treatment. Six citrin-deficient individuals received a carbohydrate-restricted/fat-enriched diet and showed normalisation of laboratory values/hepatopathy as well as age-adequate thriving. We conclude that patients with MAS-/MPC1-defects are amenable to dietary intervention and that early (genetic) diagnosis is key for initiation of proper treatment and can even be lifesaving.
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- 2022
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36. Efficacy and safety of empagliflozin in glycogen storage disease type Ib: Data from an international questionnaire.
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Grünert SC, Derks TGJ, Adrian K, Al-Thihli K, Ballhausen D, Bidiuk J, Bordugo A, Boyer M, Bratkovic D, Brunner-Krainz M, Burlina A, Chakrapani A, Corpeleijn W, Cozens A, Dawson C, Dhamko H, Milosevic MD, Eiroa H, Finezilber Y, Moura de Souza CF, Garcia-Jiménez MC, Gasperini S, Haas D, Häberle J, Halligan R, Fung LH, Hörbe-Blindt A, Horka LM, Huemer M, Uçar SK, Kecman B, Kilavuz S, Kriván G, Lindner M, Lüsebrink N, Makrilakis K, Mei-Kwun Kwok A, Maier EM, Maiorana A, McCandless SE, Mitchell JJ, Mizumoto H, Mundy H, Ochoa C, Pierce K, Fraile PQ, Regier D, Rossi A, Santer R, Schuman HC, Sobieraj P, Spenger J, Spiegel R, Stepien KM, Tal G, Tanšek MZ, Torkar AD, Tchan M, Thyagu S, Schrier Vergano SA, Vucko E, Weinhold N, Zsidegh P, and Wortmann SB
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- Adolescent, Adult, Benzhydryl Compounds, Child, Child, Preschool, Glucosides, Granulocyte Colony-Stimulating Factor therapeutic use, Humans, Infant, Infant, Newborn, Retrospective Studies, Surveys and Questionnaires, Young Adult, Glycogen Storage Disease Type I drug therapy, Glycogen Storage Disease Type I pathology, Neutropenia drug therapy
- Abstract
Purpose: This paper aims to report collective information on safety and efficacy of empagliflozin drug repurposing in individuals with glycogen storage disease type Ib (GSD Ib)., Methods: This is an international retrospective questionnaire study on the safety and efficacy of empagliflozin use for management of neutropenia/neutrophil dysfunction in patients with GSD Ib, conducted among the respective health care providers from 24 countries across the globe., Results: Clinical data from 112 individuals with GSD Ib were evaluated, representing a total of 94 treatment years. The median age at start of empagliflozin treatment was 10.5 years (range = 0-38 years). Empagliflozin showed positive effects on all neutrophil dysfunction-related symptoms, including oral and urogenital mucosal lesions, recurrent infections, skin abscesses, inflammatory bowel disease, and anemia. Before initiating empagliflozin, most patients with GSD Ib were on G-CSF (94/112; 84%). At the time of the survey, 49 of 89 (55%) patients previously treated with G-CSF had completely stopped G-CSF, and another 15 (17%) were able to reduce the dose. The most common adverse event during empagliflozin treatment was hypoglycemia, occurring in 18% of individuals., Conclusion: Empagliflozin has a favorable effect on neutropenia/neutrophil dysfunction-related symptoms and safety profile in individuals with GSD Ib., Competing Interests: Conflict of Interest All authors declare no conflicts of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2022
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37. How to proceed after "negative" exome: A review on genetic diagnostics, limitations, challenges, and emerging new multiomics techniques.
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Wortmann SB, Oud MM, Alders M, Coene KLM, van der Crabben SN, Feichtinger RG, Garanto A, Hoischen A, Langeveld M, Lefeber D, Mayr JA, Ockeloen CW, Prokisch H, Rodenburg R, Waterham HR, Wevers RA, van de Warrenburg BPC, Willemsen MAAP, Wolf NI, Vissers LELM, and van Karnebeek CDM
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- DNA, Mitochondrial, Genetic Testing methods, Phenotype, Exome Sequencing methods, Exome genetics, Genomics methods
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Exome sequencing (ES) in the clinical setting of inborn metabolic diseases (IMDs) has created tremendous improvement in achieving an accurate and timely molecular diagnosis for a greater number of patients, but it still leaves the majority of patients without a diagnosis. In parallel, (personalized) treatment strategies are increasingly available, but this requires the availability of a molecular diagnosis. IMDs comprise an expanding field with the ongoing identification of novel disease genes and the recognition of multiple inheritance patterns, mosaicism, variable penetrance, and expressivity for known disease genes. The analysis of trio ES is preferred over singleton ES as information on the allelic origin (paternal, maternal, "de novo") reduces the number of variants that require interpretation. All ES data and interpretation strategies should be exploited including CNV and mitochondrial DNA analysis. The constant advancements in available techniques and knowledge necessitate the close exchange of clinicians and molecular geneticists about genotypes and phenotypes, as well as knowledge of the challenges and pitfalls of ES to initiate proper further diagnostic steps. Functional analyses (transcriptomics, proteomics, and metabolomics) can be applied to characterize and validate the impact of identified variants, or to guide the genomic search for a diagnosis in unsolved cases. Future diagnostic techniques (genome sequencing [GS], optical genome mapping, long-read sequencing, and epigenetic profiling) will further enhance the diagnostic yield. We provide an overview of the challenges and limitations inherent to ES followed by an outline of solutions and a clinical checklist, focused on establishing a diagnosis to eventually achieve (personalized) treatment., (© 2022 The Authors. Journal of Inherited Metabolic Disease published by John Wiley & Sons Ltd on behalf of SSIEM.)
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- 2022
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38. Clinical implementation of RNA sequencing for Mendelian disease diagnostics.
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Yépez VA, Gusic M, Kopajtich R, Mertes C, Smith NH, Alston CL, Ban R, Beblo S, Berutti R, Blessing H, Ciara E, Distelmaier F, Freisinger P, Häberle J, Hayflick SJ, Hempel M, Itkis YS, Kishita Y, Klopstock T, Krylova TD, Lamperti C, Lenz D, Makowski C, Mosegaard S, Müller MF, Muñoz-Pujol G, Nadel A, Ohtake A, Okazaki Y, Procopio E, Schwarzmayr T, Smet J, Staufner C, Stenton SL, Strom TM, Terrile C, Tort F, Van Coster R, Vanlander A, Wagner M, Xu M, Fang F, Ghezzi D, Mayr JA, Piekutowska-Abramczuk D, Ribes A, Rötig A, Taylor RW, Wortmann SB, Murayama K, Meitinger T, Gagneur J, and Prokisch H
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- Alleles, Humans, Sequence Analysis, RNA methods, Exome Sequencing, RNA, Transcriptome
- Abstract
Background: Lack of functional evidence hampers variant interpretation, leaving a large proportion of individuals with a suspected Mendelian disorder without genetic diagnosis after whole genome or whole exome sequencing (WES). Research studies advocate to further sequence transcriptomes to directly and systematically probe gene expression defects. However, collection of additional biopsies and establishment of lab workflows, analytical pipelines, and defined concepts in clinical interpretation of aberrant gene expression are still needed for adopting RNA sequencing (RNA-seq) in routine diagnostics., Methods: We implemented an automated RNA-seq protocol and a computational workflow with which we analyzed skin fibroblasts of 303 individuals with a suspected mitochondrial disease that previously underwent WES. We also assessed through simulations how aberrant expression and mono-allelic expression tests depend on RNA-seq coverage., Results: We detected on average 12,500 genes per sample including around 60% of all disease genes-a coverage substantially higher than with whole blood, supporting the use of skin biopsies. We prioritized genes demonstrating aberrant expression, aberrant splicing, or mono-allelic expression. The pipeline required less than 1 week from sample preparation to result reporting and provided a median of eight disease-associated genes per patient for inspection. A genetic diagnosis was established for 16% of the 205 WES-inconclusive cases. Detection of aberrant expression was a major contributor to diagnosis including instances of 50% reduction, which, together with mono-allelic expression, allowed for the diagnosis of dominant disorders caused by haploinsufficiency. Moreover, calling aberrant splicing and variants from RNA-seq data enabled detecting and validating splice-disrupting variants, of which the majority fell outside WES-covered regions., Conclusion: Together, these results show that streamlined experimental and computational processes can accelerate the implementation of RNA-seq in routine diagnostics., (© 2022. The Author(s).)
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- 2022
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39. PPA2-associated sudden cardiac death: extending the clinical and allelic spectrum in 20 new families.
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Guimier A, Achleitner MT, Moreau de Bellaing A, Edwards M, de Pontual L, Mittal K, Dunn KE, Grove ME, Tysoe CJ, Dimartino C, Cameron J, Kanthi A, Shukla A, van den Broek F, Chatterjee D, Alston CL, Knowles CV, Brett L, Till JA, Homfray T, French P, Spentzou G, Elserafy NA, Lichkus KS, Sankaran BP, Kennedy HL, George PM, Kidd A, Wortmann SB, Fisk DG, Koopmann TT, Rafiq MA, Merker JD, Parikh S, Ahimaz P, Weintraub RG, Ma AS, Turner C, Ellaway CJ, Phillips LK, Thorburn DR, Chung WK, Kana SL, Faye-Petersen OM, Thompson ML, Janin A, McLeod K, McGowan R, McFarland R, Girisha KM, Morris-Rosendahl DJ, Hurst ACE, Turner CLS, Hamilton RM, Taylor RW, Bajolle F, Gordon CT, Amiel J, Mayr JA, and Doudney K
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- 2022
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40. Clinico-radiological features, molecular spectrum, and identification of prognostic factors in developmental and epileptic encephalopathy due to inosine triphosphate pyrophosphatase (ITPase) deficiency.
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Scala M, Wortmann SB, Kaya N, Stellingwerff MD, Pistorio A, Glamuzina E, van Karnebeek CD, Skrypnyk C, Iwanicka-Pronicka K, Piekutowska-Abramczuk D, Ciara E, Tort F, Sheidley B, Poduri A, Jayakar P, Jayakar A, Upadia J, Walano N, Haack TB, Prokisch H, Aldhalaan H, Karimiani EG, Yildiz Y, Ceylan AC, Santiago-Sim T, Dameron A, Yang H, Toosi MB, Ashrafzadeh F, Akhondian J, Imannezhad S, Mirzadeh HS, Maqbool S, Farid A, Al-Muhaizea MA, Alshwameen MO, Aldowsari L, Alsagob M, Alyousef A, AlMass R, AlHargan A, Alwadei AH, AlRasheed MM, Colak D, Alqudairy H, Khan S, Lines MA, García Cazorla MÁ, Ribes A, Morava E, Bibi F, Haider S, Ferla MP, Taylor JC, Alsaif HS, Firdous A, Hashem M, Shashkin C, Koneev K, Kaiyrzhanov R, Efthymiou S, Genomics QS, Schmitt-Mechelke T, Ziegler A, Issa MY, Elbendary HM, Striano P, Alkuraya FS, Zaki MS, Gleeson JG, Barakat TS, Bierau J, van der Knaap MS, Maroofian R, and Houlden H
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- Humans, Inosine, Inosine Triphosphate, Mutation, Prognosis, Inosine Triphosphatase, Epilepsy, Generalized, Microcephaly pathology, Pyrophosphatases genetics
- Abstract
Developmental and epileptic encephalopathy 35 (DEE 35) is a severe neurological condition caused by biallelic variants in ITPA, encoding inosine triphosphate pyrophosphatase, an essential enzyme in purine metabolism. We delineate the genotypic and phenotypic spectrum of DEE 35, analyzing possible predictors for adverse clinical outcomes. We investigated a cohort of 28 new patients and reviewed previously described cases, providing a comprehensive characterization of 40 subjects. Exome sequencing was performed to identify underlying ITPA pathogenic variants. Brain MRI (magnetic resonance imaging) scans were systematically analyzed to delineate the neuroradiological spectrum. Survival curves according to the Kaplan-Meier method and log-rank test were used to investigate outcome predictors in different subgroups of patients. We identified 18 distinct ITPA pathogenic variants, including 14 novel variants, and two deletions. All subjects showed profound developmental delay, microcephaly, and refractory epilepsy followed by neurodevelopmental regression. Brain MRI revision revealed a recurrent pattern of delayed myelination and restricted diffusion of early myelinating structures. Congenital microcephaly and cardiac involvement were statistically significant novel clinical predictors of adverse outcomes. We refined the molecular, clinical, and neuroradiological characterization of ITPase deficiency, and identified new clinical predictors which may have a potentially important impact on diagnosis, counseling, and follow-up of affected individuals., (© 2022 The Authors. Human Mutation published by Wiley Periodicals LLC.)
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- 2022
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41. Variants in Mitochondrial ATP Synthase Cause Variable Neurologic Phenotypes.
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Zech M, Kopajtich R, Steinbrücker K, Bris C, Gueguen N, Feichtinger RG, Achleitner MT, Duzkale N, Périvier M, Koch J, Engelhardt H, Freisinger P, Wagner M, Brunet T, Berutti R, Smirnov D, Navaratnarajah T, Rodenburg RJT, Pais LS, Austin-Tse C, O'Leary M, Boesch S, Jech R, Bakhtiari S, Jin SC, Wilbert F, Kruer MC, Wortmann SB, Eckenweiler M, Mayr JA, Distelmaier F, Steinfeld R, Winkelmann J, and Prokisch H
- Subjects
- Dystonia enzymology, Dystonia genetics, Epilepsy genetics, Genetic Variation, Humans, Mitochondria genetics, Mitochondrial ADP, ATP Translocases genetics, Mitochondrial Diseases enzymology, Mitochondrial Diseases genetics, Models, Molecular, Mutation, Mutation, Missense, Pedigree, Phenotype, Proteomics, Exome Sequencing, Mitochondria enzymology, Mitochondrial Proton-Translocating ATPases genetics, Nervous System Diseases enzymology, Nervous System Diseases genetics, Neurodegenerative Diseases enzymology, Neurodegenerative Diseases genetics, Neurodevelopmental Disorders enzymology, Neurodevelopmental Disorders genetics
- Abstract
Objective: ATP synthase (ATPase) is responsible for the majority of ATP production. Nevertheless, disease phenotypes associated with mutations in ATPase subunits are extremely rare. We aimed at expanding the spectrum of ATPase-related diseases., Methods: Whole-exome sequencing in cohorts with 2,962 patients diagnosed with mitochondrial disease and/or dystonia and international collaboration were used to identify deleterious variants in ATPase-encoding genes. Findings were complemented by transcriptional and proteomic profiling of patient fibroblasts. ATPase integrity and activity were assayed using cells and tissues from 5 patients., Results: We present 10 total individuals with biallelic or de novo monoallelic variants in nuclear ATPase subunit genes. Three unrelated patients showed the same homozygous missense ATP5F1E mutation (including one published case). An intronic splice-disrupting alteration in compound heterozygosity with a nonsense variant in ATP5PO was found in one patient. Three patients had de novo heterozygous missense variants in ATP5F1A, whereas another 3 were heterozygous for ATP5MC3 de novo missense changes. Bioinformatics methods and populational data supported the variants' pathogenicity. Immunohistochemistry, proteomics, and/or immunoblotting revealed significantly reduced ATPase amounts in association to ATP5F1E and ATP5PO mutations. Diminished activity and/or defective assembly of ATPase was demonstrated by enzymatic assays and/or immunoblotting in patient samples bearing ATP5F1A-p.Arg207His, ATP5MC3-p.Gly79Val, and ATP5MC3-p.Asn106Lys. The associated clinical profiles were heterogeneous, ranging from hypotonia with spontaneous resolution (1/10) to epilepsy with early death (1/10) or variable persistent abnormalities, including movement disorders, developmental delay, intellectual disability, hyperlactatemia, and other neurologic and systemic features. Although potentially reflecting an ascertainment bias, dystonia was common (7/10)., Interpretation: Our results establish evidence for a previously unrecognized role of ATPase nuclear-gene defects in phenotypes characterized by neurodevelopmental and neurodegenerative features. ANN NEUROL 2022;91:225-237., (© 2021 The Authors. Annals of Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)
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- 2022
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42. Teaching NeuroImage: Bilateral Nucleus Tractus Solitarius Lesions in Neurogenic Respiratory Failure.
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Parayil Sankaran B, Wortmann SB, Willemsen MA, and Balasubramaniam S
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- Blood Pressure, Humans, Medulla Oblongata, Respiratory Insufficiency etiology, Solitary Nucleus
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- 2022
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43. Correction: Spenger et al. Glutaric Aciduria Type I Missed by Newborn Screening: Report of Four Cases from Three Families. Int. J. Neonatal Screen . 2021, 7 , 32.
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Spenger J, Maier EM, Wechselberger K, Bauder F, Kocher M, Sperl W, Preisel M, Schiergens KA, Konstantopoulou V, Röschinger W, Häberle J, Schmitt-Mechelke T, Wortmann SB, and Fingerhut R
- Abstract
There was an error in the original publication [...].
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- 2021
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44. PPA2-associated sudden cardiac death: extending the clinical and allelic spectrum in 20 new families.
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Guimier A, Achleitner MT, Moreau de Bellaing A, Edwards M, de Pontual L, Mittal K, Dunn KE, Grove ME, Tysoe CJ, Dimartino C, Cameron J, Kanthi A, Shukla A, van den Broek F, Chatterjee D, Alston CL, Knowles CV, Brett L, Till JA, Homfray T, French P, Spentzou G, Elserafy NA, Lichkus KS, Sankaran BP, Kennedy HL, George PM, Kidd A, Wortmann SB, Fisk DG, Koopmann TT, Rafiq MA, Merker JD, Parikh S, Ahimaz P, Weintraub RG, Ma AS, Turner C, Ellaway CJ, Phillips LK, Thorburn DR, Chung WK, Kana SL, Faye-Petersen OM, Thompson ML, Janin A, McLeod K, McGowan R, McFarland R, Girisha KM, Morris-Rosendahl DJ, Hurst ACE, Turner CLS, Hamilton RM, Taylor RW, Bajolle F, Gordon CT, Amiel J, Mayr JA, and Doudney K
- Subjects
- Adolescent, Alleles, Child, Preschool, Humans, Inorganic Pyrophosphatase genetics, Inorganic Pyrophosphatase metabolism, Mitochondrial Proteins genetics, Mutation, Cardiomyopathies genetics, Death, Sudden, Cardiac etiology
- Abstract
Purpose: Biallelic hypomorphic variants in PPA2, encoding the mitochondrial inorganic pyrophosphatase 2 protein, have been recently identified in individuals presenting with sudden cardiac death, occasionally triggered by alcohol intake or a viral infection. Here we report 20 new families harboring PPA2 variants., Methods: Synthesis of clinical and molecular data concerning 34 individuals harboring five previously reported PPA2 variants and 12 novel variants, 11 of which were functionally characterized., Results: Among the 34 individuals, only 6 remain alive. Twenty-three died before the age of 2 years while five died between 14 and 16 years. Within these 28 cases, 15 died of sudden cardiac arrest and 13 of acute heart failure. One case was diagnosed prenatally with cardiomyopathy. Four teenagers drank alcohol before sudden cardiac arrest. Progressive neurological signs were observed in 2/6 surviving individuals. For 11 variants, recombinant PPA2 enzyme activities were significantly decreased and sensitive to temperature, compared to wild-type PPA2 enzyme activity., Conclusion: We expand the clinical and mutational spectrum associated with PPA2 dysfunction. Heart failure and sudden cardiac arrest occur at various ages with inter- and intrafamilial phenotypic variability, and presentation can include progressive neurological disease. Alcohol intake can trigger cardiac arrest and should be strictly avoided., (© 2021. The Author(s).)
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- 2021
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45. Congenital disorders of glycosylation with defective fucosylation.
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Hüllen A, Falkenstein K, Weigel C, Huidekoper H, Naumann-Bartsch N, Spenger J, Feichtinger RG, Schaefers J, Frenz S, Kotlarz D, Momen T, Khoshnevisan R, Riedhammer KM, Santer R, Herget T, Rennings A, Lefeber DJ, Mayr JA, Thiel C, and Wortmann SB
- Subjects
- Adolescent, Adult, Child, Child, Preschool, Female, Fibroblasts metabolism, Fibroblasts pathology, Glycoproteins, Glycosylation, Humans, Infant, Male, Treatment Outcome, Young Adult, Congenital Disorders of Glycosylation drug therapy, Congenital Disorders of Glycosylation genetics, Fucose therapeutic use, Monosaccharide Transport Proteins genetics
- Abstract
Fucosylation is essential for intercellular and intracellular recognition, cell-cell interaction, fertilization, and inflammatory processes. Only five types of congenital disorders of glycosylation (CDG) related to an impaired fucosylation have been described to date: FUT8-CDG, FCSK-CDG, POFUT1-CDG SLC35C1-CDG, and the only recently described GFUS-CDG. This review summarizes the clinical findings of all hitherto known 25 patients affected with those defects with regard to their pathophysiology and genotype. In addition, we describe five new patients with novel variants in the SLC35C1 gene. Furthermore, we discuss the efficacy of fucose therapy approaches within the different defects., (© 2021 SSIEM.)
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- 2021
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46. Expanding the phenotypic spectrum of BCS1L-related mitochondrial disease.
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Hikmat O, Isohanni P, Keshavan N, Ferla MP, Fassone E, Abbott MA, Bellusci M, Darin N, Dimmock D, Ghezzi D, Houlden H, Invernizzi F, Kamarus Jaman NB, Kurian MA, Morava E, Naess K, Ortigoza-Escobar JD, Parikh S, Pennisi A, Barcia G, Tylleskär KB, Brackman D, Wortmann SB, Taylor JC, Bindoff LA, Fellman V, and Rahman S
- Subjects
- Adolescent, Age of Onset, Child, Child, Preschool, Female, Humans, Infant, Infant, Newborn, Male, Mitochondrial Diseases complications, Retrospective Studies, ATPases Associated with Diverse Cellular Activities genetics, Electron Transport Complex III genetics, Mitochondrial Diseases genetics, Mitochondrial Diseases metabolism, Mitochondrial Diseases physiopathology
- Abstract
Objective: To delineate the full phenotypic spectrum of BCS1L-related disease, provide better understanding of the genotype-phenotype correlations and identify reliable prognostic disease markers., Methods: We performed a retrospective multinational cohort study of previously unpublished patients followed in 15 centres from 10 countries. Patients with confirmed biallelic pathogenic BCS1L variants were considered eligible. Clinical, laboratory, neuroimaging and genetic data were analysed. Patients were stratified into different groups based on the age of disease onset, whether homozygous or compound heterozygous for the c.232A>G (p.Ser78Gly) variant, and those with other pathogenic BCS1L variants., Results: Thirty-three patients were included. We found that growth failure, lactic acidosis, tubulopathy, hepatopathy and early death were more frequent in those with disease onset within the first month of life. In those with onset after 1 month, neurological features including movement disorders and seizures were more frequent. Novel phenotypes, particularly involving movement disorder, were identified in this group. The presence of the c.232A>G (p.Ser78Gly) variant was associated with significantly worse survival and exclusively found in those with disease onset within the first month of life, whilst other pathogenic BCS1L variants were more frequent in those with later symptom onset., Interpretation: The phenotypic spectrum of BCS1L-related disease comprises a continuum of clinical features rather than a set of separate syndromic clinical identities. Age of onset defines BCS1L-related disease clinically and early presentation is associated with poor prognosis. Genotype correlates with phenotype in the presence of the c.232A>G (p.Ser78Gly) variant., (© 2021 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)
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- 2021
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47. Cytosolic Phosphoenolpyruvate Carboxykinase Deficiency: Cause of Hypoglycemia-Induced Seizure and Death.
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Becker J, Haas NA, Vlaho S, Heineking B, Wortmann SB, Rabenhorst D, Thomas C, and Brunet T
- Subjects
- Child, Child, Preschool, Humans, Male, Phosphoenolpyruvate Carboxykinase (GTP) deficiency, Seizures complications, Seizures genetics, Carbohydrate Metabolism, Inborn Errors complications, Hypoglycemia complications, Hypoglycemia genetics, Liver Diseases complications
- Abstract
Cytosolic phosphoenolpyruvate carboxykinase (PEPCK) deficiency (MIM 261680, EC 4.1.1.32, encoded by PCK1) is a rare disorder of gluconeogenesis presenting with recurrent hypoglycemia, hepatic dysfunction, and lactic acidosis. We report on a previously healthy 3-year-old boy who was initially admitted under the suspicion of a febrile seizure during an upper airway infection. Diagnostic workup revealed hypoglycemia as well as a cerebral edema and ruled out an infection. After a complicated course with difficult to treat symptomatic seizures, the child died on the 5th day of admission due to progressive cerebral edema. The metabolic screening showed elevated urinary lactate and Krebs cycle intermediates in line with a primary or secondary energy deficit. Due to the unclear and fatal course, trio exome sequencing was initiated postmortem ("molecular autopsy") and revealed the diagnosis of cytosolic PEPCK deficiency based on the compound heterozygosity of a known pathogenic (c.925G > A, p.(Gly309Arg)) and a previously unreported (c.724G > A, p.(Gly242Arg)) variant in PCK1 (NM_002591.3). Sanger sequencing ruled out the disease and carrier status in three older brothers. Molecular autopsy was performed due to the unclear and fatal course. The diagnosis of a cytosolic PEPCK deficiency not only helped the family to deal with the grief, but especially took away the fear that the siblings could be affected by an unknown disease in the same manner. In addition, this case increases the genetic and phenotypic spectrum of cytosolic PEPCK deficiency., Competing Interests: None declared., (Thieme. All rights reserved.)
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- 2021
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48. PIGG variant pathogenicity assessment reveals characteristic features within 19 families.
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Tremblay-Laganière C, Maroofian R, Nguyen TTM, Karimiani EG, Kirmani S, Akbar F, Ibrahim S, Afroze B, Doosti M, Ashrafzadeh F, Babaei M, Efthymiou S, Christoforou M, Sultan T, Ladda RL, McLaughlin HM, Truty R, Mahida S, Cohen JS, Baranano K, Ismail FY, Patel MS, Lehman A, Edmondson AC, Nagy A, Walker MA, Mercimek-Andrews S, Maki Y, Sachdev R, Macintosh R, Palmer EE, Mancini GMS, Barakat TS, Steinfeld R, Rüsch CT, Stettner GM, Wagner M, Wortmann SB, Kini U, Brady AF, Stals KL, Ismayilova N, Ellard S, Bernardo D, Nugent K, McLean SD, Antonarakis SE, Houlden H, Kinoshita T, Campeau PM, and Murakami Y
- Subjects
- Humans, Membrane Proteins, Pedigree, Seizures, Virulence, Autism Spectrum Disorder, Intellectual Disability, Phosphotransferases (Alcohol Group Acceptor) genetics
- Abstract
Purpose: Phosphatidylinositol Glycan Anchor Biosynthesis, class G (PIGG) is an ethanolamine phosphate transferase catalyzing the modification of glycosylphosphatidylinositol (GPI). GPI serves as an anchor on the cell membrane for surface proteins called GPI-anchored proteins (GPI-APs). Pathogenic variants in genes involved in the biosynthesis of GPI cause inherited GPI deficiency (IGD), which still needs to be further characterized., Methods: We describe 22 individuals from 19 unrelated families with biallelic variants in PIGG. We analyzed GPI-AP surface levels on granulocytes and fibroblasts for three and two individuals, respectively. We demonstrated enzymatic activity defects for PIGG variants in vitro in a PIGG/PIGO double knockout system., Results: Phenotypic analysis of reported individuals reveals shared PIGG deficiency-associated features. All tested GPI-APs were unchanged on granulocytes whereas CD73 level in fibroblasts was decreased. In addition to classic IGD symptoms such as hypotonia, intellectual disability/developmental delay (ID/DD), and seizures, individuals with PIGG variants of null or severely decreased activity showed cerebellar atrophy, various neurological manifestations, and mitochondrial dysfunction, a feature increasingly recognized in IGDs. Individuals with mildly decreased activity showed autism spectrum disorder., Conclusion: This in vitro system is a useful method to validate the pathogenicity of variants in PIGG and to study PIGG physiological functions., (© 2021. The Author(s), under exclusive licence to the American College of Medical Genetics and Genomics.)
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- 2021
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49. Correction to: Ketogenic diet for mitochondrial disease: a systematic review on efficacy and safety.
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Zweers H, van Wegberg AMJ, Janssen MCH, and Wortmann SB
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- 2021
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50. A spoonful of L-fucose-an efficient therapy for GFUS-CDG, a new glycosylation disorder.
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Feichtinger RG, Hüllen A, Koller A, Kotzot D, Grote V, Rapp E, Hofbauer P, Brugger K, Thiel C, Mayr JA, and Wortmann SB
- Subjects
- Child, Fibroblasts metabolism, Glycoproteins, Glycosylation, Humans, Fucose, Guanosine Diphosphate Fucose metabolism
- Abstract
Congenital disorders of glycosylation are a genetically and phenotypically heterogeneous family of diseases affecting the co- and posttranslational modification of proteins. Using exome sequencing, we detected biallelic variants in GFUS (NM_003313.4) c.[632G>A];[659C>T] (p.[Gly211Glu];[Ser220Leu]) in a patient presenting with global developmental delay, mild coarse facial features and faltering growth. GFUS encodes GDP-L-fucose synthase, the terminal enzyme in de novo synthesis of GDP-L-fucose, required for fucosylation of N- and O-glycans. We found reduced GFUS protein and decreased GDP-L-fucose levels leading to a general hypofucosylation determined in patient's glycoproteins in serum, leukocytes, thrombocytes and fibroblasts. Complementation of patient fibroblasts with wild-type GFUS cDNA restored fucosylation. Making use of the GDP-L-fucose salvage pathway, oral fucose supplementation normalized fucosylation of proteins within 4 weeks as measured in serum and leukocytes. During the follow-up of 19 months, a moderate improvement of growth was seen, as well as a clear improvement of cognitive skills as measured by the Kaufmann ABC and the Nijmegen Pediatric CDG Rating Scale. In conclusion, GFUS-CDG is a new glycosylation disorder for which oral L-fucose supplementation is promising., (© 2021 The Authors. Published under the terms of the CC BY 4.0 license.)
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- 2021
- Full Text
- View/download PDF
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