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Pompe disease is an inherited progressive myopathy caused by deficiency of the lysosomal enzyme acid α-glucosidase. In 2006 enzyme replacement therapy with alglucosidase alfa was approved, which overall led to improved survival and stabilization of muscle strength and pulmonary function. However, individual treatment response varies, and some patients still deteriorate. Recently avalglucosidase alfa, a next generation ERT, was developed, which is enriched with extra mannose-6-phosphate groups aimed to increase efficacy by improved targeting of the receptor responsible for enzyme uptake in muscle tissue. A phase 3 trial with avalglucosidase alfa showed non-inferiority compared to alglucosidase alfa in both improvement in 6-minute walk test (6MWT) and forced vital capacity (FVC). However, this trial exclusively included treatment-naïve patients. We aimed to investigate whether patients with late-onset Pompe disease deteriorating despite treatment with alglucosidase alfa would benefit from a switch to avalglucosidase alfa. We included adults treated with alglucosidase alfa for at least two years who were deteriorating in pulmonary function, 6MWT and/or muscle strength over the last year(s). Patients with severe infusion associated reactions (IARs) or high anti-alglucosidase alfa antibody titers (≥1:31,250) were excluded. We assessed IARs, muscle strength and function, pulmonary function, patient reported outcome measures and development of anti-avalglucosidase alfa antibodies at three-month intervals. Planned follow-up duration is five years, in order to compare disease course before and after switching treatments. Six patients were included (one male, five females), with a median age of 45.7 years (range 42.0-54.4). Prior to switching treatments, median disease duration from symptom onset was 25 years (range 16-32) and patients had been treated with alglucosidase alfa for 15.4 years (range 7.4-16.6). Median FVC upright was 62.5% (range 45.0-83.0) and 6MWT 50.0% (range 17.5-65.9) of the predicted value. Three patients were dependent on a walking aid and two on non-invasive ventilation. Preliminary data after one year show a stable median FVC and 6MWT, 62.0% (range 44.0-87.0) and 50.3% (range 18.8-69.6) predicted respectively. Use of assistive devices or non-invasive ventilation did not change. Infusions were well tolerated without significant IARs in the first year. The highest antibody titer in any patient after switching treatments was 1:6,250. These data indicate that a switch to avalglucosidase alfa in patients deteriorating on alglucosidase alfa is safe and may result in stabilization of disease. [ABSTRACT FROM AUTHOR]

Background: Inherited metabolic diseases (IMDs) may have considerable implications for patients and their families. Despite their individual rarity, covering a spectrum of over 1800 distinct diseases, the diseases collectively exert a significant impact, with often lifelong disabilities. The United for Metabolic Diseases consortium was established to catalyze research with translation into the best possible care., Aim: To generate a translational knowledge agenda, which identifies and prioritizes research questions, directly relevant to patient care or for IMD patients and their families., Methods and Results: Following a process established by the Knowledge Institute of the Dutch Association of Medical Specialists, we generated a comprehensive translational knowledge agenda for IMDs. A multidisciplinary steering committee, composed of 12 diverse metabolic experts collected research questions through an online questionnaire using snowballing. The 462 proposed questions were categorized and prioritized during a meeting attended by 22 representatives of all stakeholder groups. The resulting top 10 research questions cover multiple themes, i.e. prediction of disease progression, development of novel tools, mechanistic insights, improved diagnostics, therapeutic integration of multi-omics techniques, assessment of impact on daily life, expanding treatment avenues, optimal study designs, effect of lifestyle interventions, and data utilization using FAIR principles., Discussion: This collective endeavor reflects the collaborative spirit needed for rare disease research. This knowledge agenda will guide funding directions and applications but will also boost interdisciplinary collaboration to push the field of IMDs research forward in a renewed UMD consortium. Patient engagement, transparency, and a comprehensive approach make this knowledge agenda a pivotal step toward addressing the pressing research needs and priorities in this domain., Competing Interests: The authors have no competing interests to declare., (© 2024 The Author(s). JIMD Reports published by John Wiley & Sons Ltd on behalf of SSIEM.)

Cystic fibrosis (CF) is incurable and chronic, causing severe multisystemic damage and long-term complications. The most prominent extrapulmonary long-term complication is CF-related diabetes, which is the most reported form of diabetes in individuals with cystic fibrosis. Here we present the first case of an individual with cystic fibrosis who developed type 2 diabetes due to obesity rather than CF-related diabetes. The type 2 diabetes went into remission due to extreme weight loss after gastric bypass surgery. To our knowledge, this case is also the first report describing the effect of bariatric surgery in a patient with CF. This case demonstrates that patients with CF may present with type 2 diabetes instead of CF-related diabetes. Differential diagnosis of these two types of diabetes is essential for optimal treatment and quality of life., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

The SARS-CoV-2 pandemic challenges healthcare systems worldwide. Within inherited metabolic disorders (IMDs) the vulnerable subgroup of intoxication-type IMDs such as organic acidurias (OA) and urea cycle disorders (UCD) show risk for infection-induced morbidity and mortality. This study (observation period February 2020 to December 2021) evaluates impact on medical health care as well as disease course and outcome of SARS-CoV-2 infections in patients with intoxication-type IMDs managed by participants of the European Registry and Network for intoxication type metabolic diseases Consortium (E-IMD). Survey's respondents managing 792 patients (n = 479 pediatric; n = 313 adult) with intoxication-type IMDs (n = 454 OA; n = 338 UCD) in 14 countries reported on 59 (OA: n = 36; UCD: n = 23), SARS-CoV-2 infections (7.4%). Medical services were increasingly requested (95%), mostly alleviated by remote technologies (86%). Problems with medical supply were scarce (5%). Regular follow-up visits were reduced in 41% (range 10%-50%). Most infected individuals (49/59; 83%) showed mild clinical symptoms, while 10 patients (17%; n = 6 OA including four transplanted MMA patients; n = 4 UCD) were hospitalized (metabolic decompensation in 30%). ICU treatment was not reported. Hospitalization rate did not differ for diagnosis or age group (p = 0.778). Survival rate was 100%. Full recovery was reported for 100% in outpatient care and 90% of hospitalized individuals. SARS-CoV-2 impacts health care of individuals with intoxication-type IMDs worldwide. Most infected individuals, however, showed mild symptoms and did not require hospitalization. SARS-CoV-2-induced metabolic decompensations were usually mild without increased risk for ICU treatment. Overall prognosis of infected individuals is very promising and IMD-specific or COVID-19-related complications have not been observed., (© 2022 The Authors. Journal of Inherited Metabolic Disease published by John Wiley & Sons Ltd on behalf of SSIEM.)

High mortality rates have been reported in historical cohorts of acute intermittent porphyria (AIP) patients. The mortality associated with (hydroxymethylbilane synthase) HMBS variant heterozygosity is unknown. This study estimates all-cause mortality in pedigrees with HMBS gene variants that cause AIP. We collected data on the lifespan of individuals in Dutch AIP pedigrees and performed analyses using the family tree mortality ratio method. This gave us standardized mortality ratios for these pedigrees compared to the Dutch general population as a primary outcome. Between 1810 and 2017, the overall mortality in these pedigrees was identical to that of the general Dutch population: (SMR 1.01, p = 0.441). However, compared with the general population the SMR was significantly higher in women aged 45−64 years (SMR 1.99, p = 0.00003), which was based on excess mortality between 1915 and 1964 (SMR 1.94, p < 0.00002). In men aged 70−74 years, the SMR was 1.55 (p = 0.0021), based on excess mortality that occurred between 1925 and 1964 (SMR 1.92, p = 0000000003). Overall, mortality from HMBS variant heterozygosity was not increased compared with the general population. Severe excess mortality occurred in young women and old men between 1915 and 1964. Heterozygotes reached a normal lifespan during the past half-century, in parallel with disease awareness and the prevention of new attacks through family counselling.

Mucopolysaccharidosis type VI (MPS VI) is a metabolic disorder caused by disease-associated variants in the Arylsulfatase B ( ARSB ) gene, resulting in ARSB enzyme deficiency, lysosomal glycosaminoglycan accumulation, and cartilage and bone pathology. The molecular response to MPS VI that results in cartilage pathology in human patients is largely unknown. Here, we generated a disease model to study the early stages of cartilage pathology in MPS VI. We generated iPSCs from four patients and isogenic controls by inserting the ARSB cDNA in the AAVS1 safe harbor locus using CRISPR/Cas9. Using an optimized chondrogenic differentiation protocol, we found Periodic acid-Schiff positive inclusions in hiPSC-derived chondrogenic cells with MPS VI. Genome-wide mRNA expression analysis showed that hiPSC-derived chondrogenic cells with MPS VI downregulated expression of genes involved in TGF-β/BMP signalling, and upregulated expression of inhibitors of the Wnt/β-catenin signalling pathway. Expression of genes involved in apoptosis and growth was upregulated, while expression of genes involved in glycosaminoglycan metabolism was dysregulated in hiPSC-derived chondrogenic cells with MPS VI. These results suggest that human ARSB deficiency in MPS VI causes changes in the transcriptional program underlying the early stages of chondrogenic differentiation and metabolism., 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 © 2022 Broeders, van Rooij, Oussoren, van Gestel, Smith, Kimber, Verdijk, Wagenmakers, van den Hout, van der Ploeg, Narcisi and Pijnappel.)

Objective: Cushing's syndrome (CS) is associated with osteoporosis and high fracture risk. Besides male sex, it is unknown which variables influence bone mineral density (BMD) at diagnosis and it is unclear to what extent BMD normalizes during long-term follow-up after treatment of CS. The aim of this study was to determine factors associated with BMD at diagnosis of CS and to determine the long-term course of BMD and fracture rate after successful treatment of CS., Design: Retrospective cross-sectional and longitudinal cohort study., Methods: Data were collected from 231 patients with CS who were treated at the Radboud University Medical Centre between 1968 and 2020., Results: At diagnosis, male sex was associated with lower Z-scores at the lumbar spine (LS) compared with female sex: -0.97s.d. (-1.45 to -0.49) after correction for possible confounders. Shorter duration of symptoms and younger age were also associated with lower Z-scores at diagnosis, while etiology of CS, urinary cortisol excretion and gonadal status were not associated with Z-scores at diagnosis. Z-scores improved up to 20 years after treatment. Fifteen years after treatment, men showed larger improvements of Z-scores than women; +2.56 (1.82-3.30) increase in LS Z-score vs +1.48 (0.96-2.00) respectively. Fracture incidence was highest during the 2 years before diagnosis and decreased after treatment., Conclusion: Male sex, younger age and shorter duration of symptoms are associated with lower BMD at diagnosis of CS. BMD continues to improve up to 20 years after treatment of CS. Fracture rate decreases after treatment of CS.

Background and Objective: Methylmalonic acidemia (MMA) and propionic acidemia (PA) are inborn errors of metabolism. While survival of MMA and PA patients has improved in recent decades, long-term outcome is still unsatisfactory. A protein restricted diet is the mainstay for treatment. Additional amino acid mixtures (AAM) can be prescribed if natural protein is insufficient. It is unknown if dietary treatment can have an impact on outcome., Design: We performed a nationwide retrospective cohort study and evaluated both longitudinal dietary treatment and clinical course of Dutch MMA and PA patients. Protein prescription was compared to the recommended daily allowances (RDA); the safe level of protein intake as provided by the World Health Organization. The association of longitudinal dietary treatment with long-term outcome was evaluated., Results: The cohort included 76 patients with a median retrospective follow-up period of 15 years (min-max: 0-48 years) and a total of 1063 patient years on a protein restricted diet. Natural protein prescription exceeded the RDA in 37% (470/1287) of all prescriptions and due to AAM prescription, the total protein prescription exceeded RDA in 84% (1070/1277). Higher protein prescriptions were associated with adverse outcomes in severely affected patients. In PA early onset patients a higher natural protein prescription was associated with more frequent AMD. In MMA vitamin B12 unresponsive patients, both a higher total protein prescription and AAM protein prescription were associated with more mitochondrial complications. A higher AAM protein prescription was associated with an increased frequency of cognitive impairment in the entire., Conclusion: Protein intake in excess of recommendations is frequent and is associated with poor outcome., Competing Interests: Conflict of interest All authors state that they have no competing interests to declare. None of the authors accepted any reimbursements, fees or funds from any organization that may in any way gain or lose financially from the results of this study. The authors have not been employed by such an organization. The authors do not have any other competing interest., (Copyright © 2021 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Pompe disease is a rare inherited metabolic and neuromuscular disorder, presenting as a spectrum, with the classic infantile form on one end and the more slowly progressive non-classic form on the other end. While being a hallmark in classic infantile Pompe disease, cardiac involvement in non-classic Pompe disease seems rare. Vascular abnormalities, such as aneurysms and arterial dolichoectasia, likely caused by glycogen accumulation in arterial walls, have been reported in non-classic Pompe patients. With this first systematic review on cardiovascular disease in non-classic Pompe disease, we aim to gain insight in the prevalence and etiology of cardiovascular disease in these patients. Forty-eight studies (eight case-control studies, 15 cohort studies and 25 case reports/series) were included. Fourteen studies reported cardiac findings, 25 studies described vascular findings, and nine studies reported both cardiac and vascular findings. Severe cardiac involvement in non-classic Pompe disease patients has rarely been reported, particularly in adult-onset patients carrying the common IVS1 mutation. There are indications that intracranial dolichoectasia and aneurysms are more prevalent in non-classic Pompe patients compared to the general population. To further investigate the prevalence of cardiovascular disease in non-classic Pompe patients, larger case-control studies that also study established cardiovascular risk factors should be conducted., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Porphyrias are rare metabolic disorders. Lack of awareness and knowledge about the clinical features of porphyrias results in diagnostic and therapeutic delays for many patients. Delays in diagnosing and treating porphyrias can result in severe, progressive morbidity (and mortality) and psychological distress for patients. This review discusses the pathophysiology, diagnosis, treatment, and follow-up of the most prevalent porphyrias: acute intermittent porphyria, porphyria cutanea tarda, and erythropoietic protoporphyria.

Introduction: New neurological symptoms in methylmalonic acidemia (MMA) patients after liver and/or kidney transplantation (LKT) are often described as metabolic stroke-like-events. Since calcineurin inhibitors (CNIs) are a well-known cause of new neurological symptoms in non-MMA transplanted patients, we investigated the incidence of CNI-induced neurotoxicity including posterior reversible encephalopathy syndrome (PRES) in post-transplanted MMA patients., Methods: We report the two MMA patients treated with LKT in our center. Additionally, we performed a systematic review of case reports/series of post-transplanted MMA patients and determined if CNI-induced neurotoxicity/PRES was a likely cause of new neurological symptoms. Definite CNI-induced neurotoxicity was defined as new neurological symptoms during CNI treatment with symptom improvement after CNI dose reduction/discontinuation. PRES was defined as CNI-induced neurotoxicity with signs of vasogenic edema on brain magnetic resonance imaging (MRI)-scan post-transplantation., Results: Our two MMA patients both developed CNI-induced neurotoxicity, one had PRES. In literature, 230 transplanted MMA patients were identified. Neurological follow-up was reported in 54 of them, of which 24 were excluded from analysis since no anti-rejection medication was reported. Thirty patients, all using CNI, were included. Sixteen patients (53%) had no new neurological symptoms post-transplantation and five patients (17%) had definite CNI neurotoxicity of whom two had PRES. Including our cases this results in a pooled incidence of 22% (7/32) definite CNI neurotoxicity and 9% PRES (3/32) in post-transplanted MMA patients on CNI., Conclusion: In MMA post-transplanted patients with new neurological symptoms CNI-induced neurotoxicity/PRES should be considered. Early recognition of CNI-induced neurotoxicity is essential to initiate dose reduction/discontinuation of CNI to minimize persistent neurologic damage and improve outcome., Concise One Sentence Take Home Message: In all post-transplanted MMA patients with new neurological symptoms CNI-induced neurotoxicity/PRES should be considered, and directly reducing the dose/discontinuation of CNI is essential., Competing Interests: This research was performed independently of all financial sponsors other than Erasmus MC, University Medical Center, (© 2020 The Authors. Journal of Inherited Metabolic Disease published by John Wiley & Sons Ltd on behalf of SSIEM.)

Background: The mucopolysaccharidoses are multisystem lysosomal storage diseases characterized by extensive skeletal deformities, including skull abnormalities. The objective of this study was to determine the incidence of craniosynostosis in the different mucopolysaccharidosis (MPS) types and its clinical consequences., Methods: In a prospective cohort study spanning 10 years, skull imaging and clinical evaluations were performed in 47 MPS patients (type I, II, VI, and VII). A total of 215 radiographs of the skull were analyzed. The presence and type of craniosynostosis, the sutures involved, progression over time, skull shape, head circumference, fundoscopy, and ventriculoperitoneal shunt (VPS) placement data were evaluated., Results: Craniosynostosis of at least one suture was present in 77% of all 47 MPS patients (≤ 6 years of age in 40% of all patients). In 32% of all MPS patients, premature closure of all sutures was seen (≤ 6 years of age in 13% of all patients). All patients with early closure had a more severe MPS phenotype, both in the neuronopathic (MPS I, II) and non-neuronopathic (MPS VI) patient groups. Because of symptomatic increased intracranial pressure (ICP), a VPS was placed in six patients, with craniosynostosis as a likely or certain causative factor for the increased pressure in four patients. One patient underwent cranial vault expansion because of severe craniosynostosis., Conclusions: Craniosynostosis occurs in the majority of MPS patients. Since the clinical consequences can be severe and surgical intervention is possible, skull growth and signs and symptoms of increased ICP should be monitored in both neuronopathic and non-neuronopathic patients with MPS.

Objective: Centripetal obesity is associated with systemic low-grade inflammation and an increased cardiovascular risk. Patients in long-term remission of Cushing's syndrome (CS) report persisting abdominal fat accumulation. However, this has previously not been adequately objectified. Therefore, we investigated the adipose tissue distribution and adipocytokine profiles of patients in long-term remission of CS., Design: Cross-sectional case-control study in a tertiary referral centre., Patients: Fifty-eight patients, in remission of CS for at least 5 years, were compared to 58 age-, gender- and BMI-matched healthy control subjects., Measurements: Measures of body composition (assessed with clinical evaluation and dual-energy X-ray absorptiometry (DEXA) scanning) and serum adipocytokine profiles., Results: Compared to the matched control subjects, patients in long-term remission of CS had a greater waist circumference (P < 0·01), a smaller thigh circumference (P < 0·01), a higher waist-to-hip ratio (P < 0·01) and a higher hip-to-thigh ratio (P < 0·01). As measured with DEXA scanning, patients had a higher percentage of truncal fat mass (P = 0·01), and the truncal fat mass to leg fat mass ratio was greater (P < 0·01). Patients had lower adiponectin levels (P < 0·01), higher leptin levels (P < 0·01) and higher resistin levels (P = 0·04) than control subjects., Conclusion: Even after long-term remission, patients who suffered from CS in the past continue to have a centripetal adipose tissue distribution and an adverse adipokine profile. This is independent of aetiology of the CS, treatment strategies, hormonal deficiencies and comorbidity, and probably contributes to the persistent increased cardiovascular risk., (© 2014 John Wiley & Sons Ltd.)