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Whole-exome sequencing was used to identify the disease gene(s) in a Spanish girl with failure to thrive, muscle weakness, mild facial weakness, elevated creatine kinase, deficiency of mitochondrial complex III and depletion of mtDNA. With whole-exome sequencing data, it was possible to get the whole mtDNA sequencing and discard any pathogenic variant in this genome. The analysis of whole exome uncovered a homozygous pathogenic mutation in thymidine kinase 2 gene ( TK2; NM&#95;004614.4:c.323 C>T, p.T108M). TK2 mutations have been identified mainly in patients with the myopathic form of mtDNA depletion syndromes. This patient presents an atypical TK2-related myopathic form of mtDNA depletion syndromes, because despite having a very low content of mtDNA (<20%), she presents a slower and less severe evolution of the disease. In conclusion, our data confirm the role of TK2 gene in mtDNA depletion syndromes and expanded the phenotypic spectrum.

We report clinical and biochemical finding from three unrelated patients presenting ONCE (Optic Neuropathy, Cardiomyopathy and Encephalopathy with lactic acidosis and combined oxidative phosphorylation deficiency) syndrome. Whole-exome sequencing (WES) of the three patients and the healthy sister of one of them was used to identify the carry gene. Clinical and biochemical findings were used to filter variants, and molecular, in silico and genetic studies were performed to characterize the candidate variants. Mitochondrial DNA (mtDNA) defects involving mutations, deletions or depletion were discarded, whereas WES uncovered a double homozygous mutation in the MTO1 gene (NM&#95;001123226:c.1510C>T, p.R504C, and c.1669G>A, p.V557M) in two of the patients and the homozygous mutation p.R504C in the other. Therefore, our data confirm p.R504C as pathogenic mutation responsible of ONCE syndrome, and p.V557M as a rare polymorphic variant., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background & Aims: Mitochondrial diseases (MD) are the most frequent inborn errors of metabolism. In affected tissues, MD can alter cellular oxygen consumption rate leading to potential decreases in whole-body resting energy expenditure (REE), but data on pediatric children are absent. We determined, using indirect calorimetry (IC), whole-body oxygen consumption (VO 2 ), carbon dioxide production (VCO 2 ), respiratory quotient (RQ) and REE in pediatric patients with MD and healthy controls. Another goal was to assess the accuracy of available predictive equations for REE estimation in this patient population., Methods: IC data were obtained under fasting and resting conditions in 20 MD patients and 27 age and gender-matched healthy peers. We determined the agreement between REE measured with IC and REE estimated with Schofield weight and FAO/WHO/UNU equations., Results: Mean values of VO 2 , VCO 2 (mL·min -1 ·kg -1 ) or RQ did not differ significantly between patients and controls (P = 0.085, P = 0.055 and P = 0.626 respectively). Accordingly, no significant differences (P = 0.086) were found for REE (kcal·day -1  kg -1 ) either. On the other hand, although we found no significant differences between IC-measured REE and Schofield or FAO/WHO/UNU-estimated REE, Bland-Altman analysis revealed wide limits of agreement and there were some important individual differences between IC and equation-derived REE., Conclusions: VO 2 , VCO 2 , RQ and REE are not significantly altered in pediatric patients with MD compared with healthy controls. The energy demands of pediatric patients with MD should be determined based on IC data in order to provide the best possible personalized nutritional management for these children., (Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

We report the clinical and biochemical findings from two unrelated patients who presented with a novel syndrome: encephalopathy, intellectual disability, severe hypotonia, chorea and optic atrophy. Whole exome sequencing (WES) uncovered a homozygous mutation in the ATP8A2 gene (NM&#95;016529:c.1287G > T, p.K429N) in one patient and compound heterozygous mutations (c.1630G > C, p.A544P and c.1873C > T, p.R625W) in the other. Only one haploinsufficiency case and a family with a homozygous mutation in ATP8A2 gene (c.1128C > G, p.I376M) have been described so far, with phenotypes that differed slightly from the patients described herein. In conclusion, our data expand both the genetic and phenotypic spectrum associated with ATP8A2 gene mutations.

We report the clinical and genetic findings in a Spanish boy who presented MEGDEL syndrome, a very rare inborn error of metabolism. Whole-exome sequencing uncovered a new homozygous mutation in the serine active site containing 1 (SERAC1) gene, which is essential for both mitochondrial function and intracellular cholesterol trafficking. Functional studies in patient fibroblasts showed that p.D224G mutation affects the intracellular cholesterol trafficking. Only three missense mutations in this gene have been described before, being p.D224G the first missense mutation outside of the SERAC1 serine-lipase domain. Therefore, we conclude that the defect in cholesterol trafficking is not limited to alterations in this specific part of the protein.

Background and Objectives: There are conflicting views as to whether testing for biotinidase deficiency (BD) ought to be incorporated into universal newborn screening (NBS) programs. The aim of this study was to evaluate the cost-effectiveness of adding BD to the panel of conditions currently screened under the national NBS program in Spain., Methods: We used information from the regional NBS program for BD that has been in place in the Spanish region of Galicia since 1987. These data, along with other sources, were used to develop a cost-effectiveness decision model that compared lifetime costs and health outcomes of a national birth cohort of newborns with and without an early detection program. The analysis took the perspective of the Spanish National Health Service. Effectiveness was measured in terms of quality-adjusted life years (QALYs). We undertook extensive sensitivity analyses around the main model assumptions, including a probabilistic sensitivity analysis., Results: In the base case analysis, NBS for BD led to higher QALYs and higher health care costs, with an estimated incremental cost per QALY gained of $24,677. Lower costs per QALY gained were found when conservative assumptions were relaxed, yielding cost savings in some scenarios. The probability that BD screening was cost-effective was estimated to be >70% in the base case at a standard threshold value., Conclusions: This study indicates that NBS for BD is likely to be a cost-effective use of resources., (Copyright © 2015 by the American Academy of Pediatrics.)

Background: Carnitine-acylcarnitine translocase (CACT) deficiency is a rare autosomal recessive disease in the mitochondrial transport of long-chain fatty acids. Despite early diagnosis and treatment, the disease still has a high mortality rate., Methods: Clinical symptoms, long-term follow-up, and biochemical and molecular results of four cases are described and compared with the reviewed literature data of 55 cases., Results: Two cases with neonatal onset, carrying in homozygosity the novel variant sequences p.Gly20Asp (c.59G>A) and p.Arg179Gly (c.536A>G), died during an intercurrent infectious process in the first year of life despite adequate dietetic treatment (frequent feeding, high-carbohydrate/low-fat diet, MCT, carnitine). The other two cases, one with infantile onset and the other diagnosed in the newborn period after a previous affected sibling, show excellent development at 4 and 16 years of age under treatment. The review shows that the most frequent presenting symptoms of CACT deficiency are hypoketotic hypoglycemia, hyperammonemia, hepatomegaly, cardiomyopathy and/or arrhythmia, and respiratory distress. The onset of symptoms is predominantly neonatal in 82% and infantile in 18%. The mortality rate is high (65%), most in the first year of life due to myocardiopathy or sudden death. Outcomes seem to correlate better with the absence of cardiac disease and with a higher long-chain fatty acid oxidation rate in cultured fibroblasts than with residual enzyme activity., Conclusion: Diagnosis before the occurrence of clinical symptoms by tandem MS-MS and very early therapeutic intervention together with good dietary compliance could lead to a better prognosis, especially in milder clinical cases.

Background: Kearns-Sayre syndrome (KSS) is a mitochondrial DNA deletion syndrome that presents with profound cerebral folate deficiency and other features. Preliminary data support the notion that folinic acid therapy might be useful in the treatment of KSS patients. Our aim was to assess the clinical and neuroimaging outcomes of KSS patients receiving folinic acid therapy., Patients: We recruited eight patients with diagnoses of KSS. Four cases were treated at 12 de Octubre Hospital, and the other two cases were treated at Sant Joan de Déu Hospital. Two patients refused to participate in the treatment protocol., Methods: Clinical, biochemical and neuroimaging data (magnetic resonance imaging or computed tomography scan) were collected in baseline conditions and at different time points after the initiation of therapy. Cerebrospinal fluid 5-methyltetrahydrofolate levels were analysed with HPLC and fluorescence detection. Large-scale mitochondrial DNA deletions were analysed by Southern blot., Treatment Protocol: The follow-up periods ranged from one to eight years. Cases 1-4 received oral folinic acid at a dose of 1 mg/kg/day, and cases 6 and 8 received 3 mg/kg/day., Results: No adverse effects of folinic acid treatment were observed. Cerebral 5-methyltetrahydrofolate deficiencies were observed in all cases in the baseline conditions. Moreover, all three patients who accepted lumbar puncture after folinic acid therapy exhibited complete recoveries of their decreased basal cerebrospinal fluid 5-methyltetrahydrofolate levels to normal values. Two cases neurologically improved after folinic therapy. Disease worsened in the other patients. Post-treatment neuroimaging was performed for the 6 cases that received folinic acid therapy. One patient exhibited improvements in white matter abnormalities. The remaining patients displayed progressions in subcortical cerebral white matter, the cerebellum and cerebral atrophy., Conclusions: Four patients exhibited clinical and radiological progression of the disease following folinic acid treatment. Only one patient who was treated in an early stage of the disease exhibited both neurological and radiological improvements following elevated doses of folinic acid, and an additional patient experienced neurological improvement. Early treatment with high-dose folinic acid therapy seems to be advisable for the treatment of KSS., Trial Registration: Eudrac T2007-00-6748-23.

Background: Advances in the diagnosis and treatment of urea cycle disorders (UCDs) have led to a higher survival rate. The purpose of this study is to describe the characteristics of patients with urea cycle disorders in Spain., Methods: Observational, cross-sectional and multicenter study. Clinical, biochemical and genetic data were collected from patients with UCDs, treated in the metabolic diseases centers in Spain between February 2012 and February 2013, covering the entire Spanish population. Heterozygous mothers of patients with OTC deficiency were only included if they were on treatment due to being symptomatic or having biochemistry abnormalities., Results: 104 patients from 98 families were included. Ornithine transcarbamylase deficiency was the most frequent condition (64.4%) (61.2% female) followed by type 1 citrullinemia (21.1%) and argininosuccinic aciduria (9.6%). Only 13 patients (12.5%) were diagnosed in a pre-symptomatic state. 63% of the cases presented with type intoxication encephalopathy. The median ammonia level at onset was 298 μmol/L (169-615). The genotype of 75 patients is known, with 18 new mutations having been described. During the data collection period four patients died, three of them in the early days of life. The median current age is 9.96 years (5.29-18), with 25 patients over 18 years of age. Anthropometric data, expressed as median and z-score for the Spanish population is shown. 52.5% of the cases present neurological sequelae, which have been linked to the type of disease, neonatal onset, hepatic failure at diagnosis and ammonia values at diagnosis. 93 patients are following a protein restrictive diet, 0.84 g/kg/day (0.67-1.10), 50 are receiving essential amino acid supplements, 0.25 g/kg/day (0.20-0.45), 58 arginine, 156 mg/kg/day (109-305) and 45 citrulline, 150 mg/kg/day (105-199). 65 patients are being treated with drugs: 4 with sodium benzoate, 50 with sodium phenylbutyrate, 10 with both drugs and 1 with carglumic acid., Conclusions: Studies like this make it possible to analyze the frequency, natural history and clinical practices in the area of rare diseases, with the purpose of knowing the needs of the patients and thus planning their care.

We describe a West syndrome (WS) patient with unidentified etiology that evolved to Lennox-Gastaut syndrome. The mitochondrial respiratory chain of the patient showed a simple complex I deficiency in fibroblasts. Whole-exome sequencing (WES) uncovered two heterozygous mutations in NDUFV2 gene that were reassigned to a pseudogene. With the WES data, it was possible to obtain whole mitochondrial DNA sequencing and to identify a heteroplasmic variant in the MT-ND1 (MTND1) gene (m.3946G>A, p.E214K). The expression of the gene in patient fibroblasts was not affected but the protein level was significantly reduced, suggesting that protein stability was affected by this mutation. The lower protein level also affected assembly of complex I and supercomplexes (I/III2 /IV and I/III2 ), leading to complex I deficiency. While ATP levels at steady state under stress conditions were not affected, the amount of ROS produced by complex I was significantly increased., (© 2013 WILEY PERIODICALS, INC.)

Background: HUPRA syndrome is a rare mitochondrial disease characterized by hyperuricemia, pulmonary hypertension, renal failure in infancy and alkalosis. This syndrome was previously described in three patients with a homozygous mutation c.1169A > G (p.D390G) in SARS2, encoding the mitochondrial seryl-tRNA synthetase., Case Presentation: Here we report the clinical and genetic findings in a girl and her brother. Both patients were clinically diagnosed with the HUPRA syndrome. Analysis of the pedigree identified a new homozygous mutation c.1205G > A (p.R402H) in SARS2 gene. This mutation is very rare in the population and it is located at the C-terminal globular domain of the homodimeric enzyme very close to p.D390G., Conclusion: Several data support that p.R402H mutation in SARS2 is a new cause of HUPRA syndrome.

Background: Conradi-Hünermann-Happle syndrome (CDPX2, OMIM 302960) is an inherited X-linked dominant variant of chondrodysplasia punctata which primarily affects the skin, bones and eyes. CDPX2 results from mutations in EBP (emopamil binding protein), and presents with increased levels of sterol precursors 8(9)-cholesterol and 8-dehydrocholesterol., Objectives: To expand the understanding of CDPX2, clinically, biochemically and genetically., Methods: We present one of the largest series reported to date, including 13 female patients belonging to nine Spanish families. Patients were studied biochemically using gas chromatography-mass spectrometry, genetically using polymerase chain reaction and in their methylation status using the HUMARA assay., Results: In our cases, there was a clear relationship between abnormal sterol profile and the EBP gene mutation. We describe three novel mutations in the EBP gene. EBP mutations were inherited in three out of nine families and were sporadic in the remaining cases., Conclusions: No clear genotype-phenotype correlation was found. Patients' biochemical profiles did not reveal a relationship between sterol profiles and severity of disease. A skewed X-chromosome inactivation may explain the clinical phenotype in CDPX2 in some familial cases., (© 2011 The Authors. BJD © 2011 British Association of Dermatologists.)

We report, for the first time, a patient with an overlap MERRF-NARP syndrome who carries the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. The mutation was heteroplamic and more abundant in her muscle and fibroblast than in blood from her oligosymptomatic mother. Single muscle fiber analysis revealed that the proportion of mutant mtDNA in ragged red fibers was higher than that in normal fibers. Combined defects of mitochondrial respiratory chain complexes were detected in muscle, fibroblasts and transmitochondrial hybrid cells. Significant reduction of total ATP and mitochondrial membrane potential and an increased production of reactive oxygen species were observed., (Copyright © 2011 Elsevier B.V. and Mitochondria Research Society. All rights reserved. All rights reserved.)

Background and Objective: To evaluate clinical, biochemical and genetic findings of two series of patients with biotinidase deficiency., Patients and Method: Fifteen cases detected through newborn screening and six through selective screening for hearing loss or metabolic disease., Results: No patient detected by neonatal screening had symptoms and only one case with partial biotinidase activity developed myoclonic seizures that resolved with biotin. More common mutations found among this group were p.D444H and the double mutation [p.D444H;p.A171T]. However, neurological and hearing manifestations predominated among the six symptomatic cases and mutations p.L32fs, p.G34fs, p.T401I, p.D444H, p.T532M and the novel one p.L466fs were identified. Patients with profound biotinidase deficiency and/or clinical signs were treated with pharmacological doses of biotin (10-30mg daily)., Conclusion: Biotinidase deficiency must be included in the newborn screening programmes in order to begin early treatment even in partial forms. Different mutations found in both series of patients suggest that routine genetic procedure of the BTD gene by direct sequencing might be useful to assign patients to the partial or profound form of the disease., (Copyright © 2010 Elsevier España, S.L. All rights reserved.)

We report two cases of type 1 Gaucher's disease in childhood and their outcomes after 9 years of enzyme replacement therapy. The first case concerns a 6-year-old boy who was diagnosed with Gaucher's disease after developing petechial exanthema, thrombocytopenia, anemia and hepatosplenomegaly, coinciding with chickenpox. The second case involves a 9-year-old girl who was referred to our unit. She had hepatosplenomegaly since 4-month-old and subsequently developed thrombocytopenia. Both patients have the N370S/L444P mutation. Enzyme replacement therapy was started with 60 U/kg imiglucerase every 2 weeks at the age of 6 and 9 years, respectively. In both patients, the therapeutic goals were achieved and maintained throughout treatment with a dose of 30 U/kg., (Copyright © 2011 Elsevier España S.L. All rights reserved.)

Mitochondrial DNA depletion syndrome (MDS) is a group of disorders characterized by a quantitative reduction of the mitochondrial DNA copy number and inherited as autosomal recessive traits. Patients affected by this group of diseases present with a wide variety of symptoms depending on the altered gene. MPV17 is one of the genes causing combined encephalopathy and liver failure and at present there is no treatment for this devastating disease. The gene codes for an inner mitochondrial membrane protein, but its function is still unknown, and therefore, the only way to offer prenatal diagnosis relies on DNA studies. Consequently, mutations have to be well characterized. We previously described a patient homozygous for a novel intronic mutation in the MPV17 gene (c.70 + 5G > A). Here we report the use of a functional splicing assay based on the use of minigenes to support that c.70 + 5G > A mutation is disease causing. We carried out three prenatal diagnoses on three consecutive pregnancies of the previously described family. After two affected fetuses, a healthy baby was born homozygous for the wild-type allele.

Background: With improvements in the treatment of children with organic acidaemias (OA), the number surviving to adulthood is increasing. To plan appropriate services for their care it is important to know what their needs are., Objective: To describe the clinical and social problems affecting adult patients with OA., Patients and Methods: We reviewed the medical records of 15 adult patients diagnosed with OA. Social attainment (housing, schooling and occupation) was analysed. Nutritional status was evaluated by body mass index (BMI) and laboratory studies. Neurological and visceral complications were noted. Cognitive outcome was evaluated by psychometric testing and/or educational attainment., Results: Seven had methylmalonic acidaemia (MMA), 4 isovaleric acidaemia (IVA) and 4 propionic acidaemia (PA). Ten were female, and median age was 23.5 years (range 18-48). All but three had late-onset disease. Two patients became pregnant during follow up. Four patients had obtained university degrees and were working. Three-quarters of the patients required some kind of social support. All had a good nutritional status. Height was normal in IVA and 3 PA patients. Osteoporosis was present in 2 out of 8 patients assessed. A variety of neurocognitive or visceral complications were seen in two-thirds of the patients. Metabolic decompensations were unusual., Conclusions: The approach to adult patients with OA has to be multidisciplinary, with the clinician and dietician as the core of the team, but with the collaboration of clinical nurses specialists, social workers and other specialist services and the support of a biochemical and molecular laboratory.

It has recently been reported that mutations in MPV17 gene may be causative of mtDNA depletion syndrome (MDS). Patients with this alteration presented with severe liver failure, hypoglycemia, growth retardation and neurological symptoms during the first year of life. We report on the clinical, biochemical and molecular findings of a patient presenting with lethal hepatopathy, polyneuropathy, neurological regression and leukodystrophy associated with mutations in MPV17. Mitochondrial respiratory chain activities were low in liver and within reference values in muscle. However, levels of mtDNA were markedly reduced both in muscle and liver. A novel homozygous mutation in MPV17, c.70+5G>A (IVS1+5G>A), was identified. This intronic change causes the full-length cDNA loss, probably due to loss of strength of the splice donor site of exon 1. Western blot analysis, performed in liver homogenates, further corroborates these results as the amount of patient's protein was highly reduced, or almost absent, compared with that of controls. We also identified an additional alternative spliced form in controls and in the patient, due to exon 2 skipping, that has not previously been reported.

We studied renal involvement in 42 children with mitochondrial diseases (MDs). The diagnosis of MD was established by morphological, biochemical, and molecular genetic criteria. Renal disease was considered when patients had renal failure, nephrotic syndrome, Fanconi's syndrome or any symptomatic renal alteration. Mild tubular disorder was established if they had abnormal laboratory findings with no apparent clinical symptom. Renal involvement was found in 21 children (50%), of whom 8 had an apparent clinical picture and 13 a mild tubular disorder. Five patients with renal disease showed Debré-Toni-Fanconi's syndrome, 2 of them with decreased glomerular filtration rate (GFR). One case had nephrotic syndrome, another one presented decreased GFR, and the last one had a neurogenic bladder and bilateral hydronephrosis. Patients with mild renal disease showed tubular dysfunction with normal GFR. Renal involvement is frequent and present in about half of the children with MD. Thus, studies for evaluating kidney function should be performed on children with MD. Conversely, patients with tubulopathy of unknown origin or progressive renal disease should be investigated for the existence of MD, especially if associated with involvement of other organs or tissues. Southern blot analysis to search for large-scale mitochondrial DNA (mtDNA) rearrangements should be performed for patients with MD and kidney involvement.

CDG Ie is caused by a deficiency of dolichol-phosphate-mannose synthase 1 (DPM1), an enzyme involved in N-glycan assembly in the endoplasmic reticulum. Three proteins are known to be part of the synthase complex: DPM 1, DPM2 and DPM3. Only mutations in DPM1, the catalytic subunit, have been described in three families. One was homozygous for the c274C>G (R92G) mutation in DPM1 and two others were compound heterozygous for R92G and a c628delC deletion or a c331-343del13, respectively. Clinical features were a severe infantile encephalopathy, early intractable seizures, acquired microcephaly, and some dysmorphic features. We report a patient with milder symptoms: microcephaly, dysmorphic features, developmental delay, optic atrophy, and cerebellar dysfunction without cerebellar atrophy. The patient is homozygous for a new mutation in exon 9 of the DPM1 gene (c742T>C (S248P)). Our findings extend the spectrum of CDG Ie.

We report a 12-month-old boy with renal hypouricemia who presented with crying due to obstructing vesicourethral uric acid stones. Metabolic study revealed persistent acidic urine with normal blood pH, and hypouricemia (1.4-1.7 mg/dl) with an increased ratio of uric acid clearance to creatinine clearance (24-32 %). Pyrazinamide produced no response but the patient showed a positive response to benzbromarone. These findings were consistent with a presecretory defect. No other tubular dysfunctions, such as renal glycosuria, aminoaciduria or phosphaturia were found. The patient underwent surgical treatment and was subsequently treated with potassium citrate. After a 2-year follow-up, he remains asymptomatic, despite persistent hyperuricosuria. To our knowledge, this is the youngest reported case of renal hypouricemia and lithiasis.

Objective: Rational use of voiding cystourethrography (VCUG) is imperative, as it is an invasive procedure exposing the child to ionizing radiation and other well documented risks. The objective of this study was to contribute to the achievement of a reduction in the irradiation dose in VCUG., Patients and Methods: We reviewed the medical records of a consecutive sample of 125 children that underwent VCUG in our hospital between January 1995 and June 1996., Results: Of the 125 VCUGs, 100 were normal, 13 showed vesicoureteric reflux grade II or higher, and 12 of them presented with other anomalies. The indication for VCUG was febrile UTI in 54 children, hydronephrosis detected prenatally in 12 and other causes in 60 children. It is important to note that children with vesicoureteric reflux presented as febrile UTI or fetal hydronephrosis. The age was significantly lower in the reflux group (p < 0.01). Eleven of the 13 children with vesicoureteric reflux were less than one year of age. Ultrasound anomalies and renal scarring in Tc99 DMSA were seen in a larger proportion in the reflux group. Preliminary X-rays showed anomalies in only 3 of 125 cases., Conclusions: 1) Vesicoureteric reflux is related to febrile UTI and fetal hydronephrosis. The other indications are questionable. 2) VCGU is not recommended following the first UTI in the evaluation of children 6 years of age or older who have a normal ultrasound and Tc99 DMSA. 3) VCUG could be substituted by a nuclear cystogram in girls who do not have a history of voiding dysfunction. 4) A preliminary X-ray is not justified.