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1.
J Inherit Metab Dis ; 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31339582

RESUMO

Transport And Golgi Organization protein 2 (TANGO2) deficiency has recently been identified as a rare metabolic disorder with a distinct clinical and biochemical phenotype of recurrent metabolic crises, hypoglycemia, lactic acidosis, rhabdomyolysis, arrhythmias, and encephalopathy with cognitive decline. We report nine subjects from seven independent families, and we studied muscle histology, respiratory chain enzyme activities in skeletal muscle and proteomic signature of fibroblasts. All nine subjects carried autosomal recessive TANGO2 mutations. Two carried the reported deletion of exons 3 to 9, one homozygous, one heterozygous with a 22q11.21 microdeletion inherited in trans. The other subjects carried three novel homozygous (c.262C>T/p.Arg88*; c.220A>C/p.Thr74Pro; c.380+1G>A), and two further novel heterozygous (c.6_9del/p.Phe6del); c.11-13delTCT/p.Phe5del mutations. Immunoblot analysis detected a significant decrease of TANGO2 protein. Muscle histology showed mild variation of fiber diameter, no ragged-red/cytochrome c oxidase-negative fibers and a defect of multiple respiratory chain enzymes and coenzyme Q10 (CoQ10 ) in two cases, suggesting a possible secondary defect of oxidative phosphorylation. Proteomic analysis in fibroblasts revealed significant changes in components of the mitochondrial fatty acid oxidation, plasma membrane, endoplasmic reticulum-Golgi network and secretory pathways. Clinical presentation of TANGO2 mutations is homogeneous and clinically recognizable. The hemizygous mutations in two patients suggest that some mutations leading to allele loss are difficult to detect. A combined defect of the respiratory chain enzymes and CoQ10 with altered levels of several membrane proteins provides molecular insights into the underlying pathophysiology and may guide rational new therapeutic interventions.

2.
Hum Mutat ; 40(10): 1731-1748, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31045291

RESUMO

Mutations in either the mitochondrial or nuclear genomes are associated with a diverse group of human disorders characterized by impaired mitochondrial respiration. Within this group, an increasing number of mutations have been identified in nuclear genes involved in mitochondrial RNA metabolism, including ELAC2. The ELAC2 gene codes for the mitochondrial RNase Z, responsible for endonucleolytic cleavage of the 3' ends of mitochondrial pre-tRNAs. Here, we report the identification of 16 novel ELAC2 variants in individuals presenting with mitochondrial respiratory chain deficiency, hypertrophic cardiomyopathy (HCM), and lactic acidosis. We provide evidence for the pathogenicity of the novel missense variants by studying the RNase Z activity in an in vitro system. We also modeled the residues affected by a missense mutation in solved RNase Z structures, providing insight into enzyme structure and function. Finally, we show that primary fibroblasts from the affected individuals have elevated levels of unprocessed mitochondrial RNA precursors. Our study thus broadly confirms the correlation of ELAC2 variants with severe infantile-onset forms of HCM and mitochondrial respiratory chain dysfunction. One rare missense variant associated with the occurrence of prostate cancer (p.Arg781His) impairs the mitochondrial RNase Z activity of ELAC2, suggesting a functional link between tumorigenesis and mitochondrial RNA metabolism.

3.
N Engl J Med ; 380(15): 1433-1441, 2019 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-30970188

RESUMO

We report an inborn error of metabolism caused by an expansion of a GCA-repeat tract in the 5' untranslated region of the gene encoding glutaminase (GLS) that was identified through detailed clinical and biochemical phenotyping, combined with whole-genome sequencing. The expansion was observed in three unrelated patients who presented with an early-onset delay in overall development, progressive ataxia, and elevated levels of glutamine. In addition to ataxia, one patient also showed cerebellar atrophy. The expansion was associated with a relative deficiency of GLS messenger RNA transcribed from the expanded allele, which probably resulted from repeat-mediated chromatin changes upstream of the GLS repeat. Our discovery underscores the importance of careful examination of regions of the genome that are typically excluded from or poorly captured by exome sequencing.


Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/genética , Ataxia/genética , Deficiências do Desenvolvimento/genética , Glutaminase/deficiência , Glutaminase/genética , Glutamina/metabolismo , Repetições de Microssatélites , Mutação , Atrofia/genética , Cerebelo/patologia , Pré-Escolar , Feminino , Genótipo , Glutamina/análise , Humanos , Masculino , Fenótipo , Reação em Cadeia da Polimerase , Sequenciamento Completo do Genoma
4.
Nutrients ; 11(3)2019 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-30823411

RESUMO

Introduction: In phenylketonuria (PKU), evidence suggests that casein glycomacropeptide supplemented with rate-limiting amino acids (CGMP-AA) is associated with better protein utilisation and less blood phenylalanine (Phe) variability. Aim: To study the impact of CGMP-AA on blood Phe variability using 3 different dietary regimens in children with PKU. Methods: This was a 6-week randomised controlled cross-over study comparing CGMP-AA vs. Phe-free l-amino acids (l-AA) assessing blood Phe and tyrosine (Tyr) variability over 24 h in 19 children (7 boys) with PKU, with a median age of 10 years (6⁻16). Subjects were randomised to 3 dietary regimens: (1) R1, CGMP-AA and usual dietary Phe (CGMP + Phe); (2) R2, CGMP-AA - Phe content of CGMP-AA from usual diet (CGMP - Phe); and (3) R3, l-AA and usual dietary Phe. Each regimen was administered for 14 days. Over the last 48 h on days 13 and 14, blood spots were collected every 4 h at 08 h, 12 h, 16 h, 20 h, 24 h, and 04 h. Isocaloric intake and the same meal plan and protein substitute dosage at standardised times were maintained when blood spots were collected. Results: Eighteen children completed the study. Median Phe concentrations over 24 h for each group were (range) R1, 290 (30⁻580), R2, 220 (10⁻670), R3, 165 (10⁻640) µmol/L. R1 vs. R2 and R1 vs. R3 p < 0.0001; R2 vs. R3 p = 0.0009. There was a significant difference in median Phe at each time point between R1 vs. R2, p = 0.0027 and R1 vs. R3, p < 0.0001, but not between any time points for R2 vs. R3. Tyr was significantly higher in both R1 and R2 [70 (20⁻240 µmol/L] compared to R3 [60 (10⁻200) µmol/L]. In children < 12 years, blood Phe remained in the target range (120⁻360 µmol/L), over 24 h, for 75% of the time in R1, 72% in R2 and 64% in R3; for children aged ≥ 12 years, blood Phe was in target range (120⁻600 µmol/L) in R1 and R2 for 100% of the time, but 64% in R3. Conclusions: The residual Phe in CGMP-AA increased blood Phe concentration in children. CGMP-AA appears to give less blood Phe variability compared to l-AA, but this effect may be masked by the increased blood Phe concentrations associated with its Phe contribution. Reducing dietary Phe intake to compensate for CGMP-AA Phe content may help.


Assuntos
Caseínas/administração & dosagem , Caseínas/farmacologia , Fragmentos de Peptídeos/administração & dosagem , Fragmentos de Peptídeos/farmacologia , Fenilalanina/sangue , Tirosina/sangue , Criança , Suplementos Nutricionais , Feminino , Humanos , Masculino , Fenilalanina/metabolismo , Fenilcetonúrias , Tirosina/metabolismo
5.
Brain ; 142(1): 50-58, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30576410

RESUMO

Physical stress, including high temperatures, may damage the central metabolic nicotinamide nucleotide cofactors [NAD(P)H], generating toxic derivatives [NAD(P)HX]. The highly conserved enzyme NAD(P)HX dehydratase (NAXD) is essential for intracellular repair of NAD(P)HX. Here we present a series of infants and children who suffered episodes of febrile illness-induced neurodegeneration or cardiac failure and early death. Whole-exome or whole-genome sequencing identified recessive NAXD variants in each case. Variants were predicted to be potentially deleterious through in silico analysis. Reverse-transcription PCR confirmed altered splicing in one case. Subject fibroblasts showed highly elevated concentrations of the damaged cofactors S-NADHX, R-NADHX and cyclic NADHX. NADHX accumulation was abrogated by lentiviral transduction of subject cells with wild-type NAXD. Subject fibroblasts and muscle biopsies showed impaired mitochondrial function, higher sensitivity to metabolic stress in media containing galactose and azide, but not glucose, and decreased mitochondrial reactive oxygen species production. Recombinant NAXD protein harbouring two missense variants leading to the amino acid changes p.(Gly63Ser) and p.(Arg608Cys) were thermolabile and showed a decrease in Vmax and increase in KM for the ATP-dependent NADHX dehydratase activity. This is the first study to identify pathogenic variants in NAXD and to link deficient NADHX repair with mitochondrial dysfunction. The results show that NAXD deficiency can be classified as a metabolite repair disorder in which accumulation of damaged metabolites likely triggers devastating effects in tissues such as the brain and the heart, eventually leading to early childhood death.


Assuntos
Hidroliases/deficiência , Doenças Neurodegenerativas/genética , Pré-Escolar , Simulação por Computador , Feminino , Febre/complicações , Febre/metabolismo , Fibroblastos/metabolismo , Vetores Genéticos , Humanos , Hidroliases/genética , Lactente , Cinética , Lentivirus , Masculino , Mitocôndrias/metabolismo , Mutação , NAD/análogos & derivados , NAD/metabolismo , Doenças Neurodegenerativas/complicações , Doenças Neurodegenerativas/metabolismo , Cultura Primária de Células , Sequenciamento Completo do Genoma
6.
Nutr Hosp ; 35(1): 237-244, 2018 Jan 10.
Artigo em Espanhol | MEDLINE | ID: mdl-29565174

RESUMO

INTRODUCTION: 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase deficiency is an autosomal recessive disorder that usually presents in the neonatal period with vomiting, metabolic acidosis, hypoglycemia and absent ketonuria. Few cases are reported in the literature, and optimal dietary management and long term outcome are not fully understood. CASE REPORT: We report a 2 year old girl with HMG-CoA-lyase deficiency who had limited fasting tolerance on a low protein diet, with several recurrent hospital admissions with severe hypoketotic hypoglycaemia and metabolic acidosis. We also review the dietary management and outcome of other reported cases in the literature. DISCUSSION: In order to define optimal dietary treatment, it is important to collect higher numbers of case studies with detailed dietary management, fasting times and outcome.


Assuntos
Acetil-CoA C-Acetiltransferase/deficiência , Erros Inatos do Metabolismo dos Aminoácidos/dietoterapia , Acidose/dietoterapia , Acidose/etiologia , Pré-Escolar , Dieta com Restrição de Proteínas , Nutrição Enteral , Feminino , Gastrostomia , Humanos , Hipoglicemia/dietoterapia , Hipoglicemia/etiologia
7.
Mol Genet Metab ; 123(4): 479-487, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29526614

RESUMO

Elosulfase alfa is an enzyme replacement therapy for Morquio A syndrome (mucopolysaccharidosis IVA), a multisystemic progressive lysosomal storage disorder. This report includes the primary treatment outcomes and immunogenicity profile of elosulfase alfa in patients with Morquio A syndrome from 2 sequential studies, MOR-002 (ClinicalTrials.govNCT00884949) and MOR-100 (NCT01242111), representing >5 years of clinical study data. MOR-002 was an open-label, single-arm phase 1/2 study that evaluated the pharmacokinetics, safety, immunogenicity, and preliminary efficacy of 3 sequential doses of elosulfase alfa (0.1, 1.0, and 2.0 mg/kg/week) in patients with Morquio A syndrome (n = 20) over 36 weeks, followed by an optional 36- to 48-week treatment period using elosulfase alfa 1.0 mg/kg once weekly (qw). During the 0.1 mg/kg dosing phase, 1 patient discontinued due to a type I hypersensitivity adverse event (AE), and that patient's sibling voluntarily discontinued in the absence of AEs. An additional patient discontinued due to recurrent infusion reactions during the 1.0 mg/kg continuation phase. The remaining 17 patients completed MOR-002 and enrolled in MOR-100, an open-label, long-term extension study that further evaluated safety and clinical outcomes with elosulfase alfa administered at 2.0 mg/kg qw. During the course of MOR-100, patients were given the option of receiving elosulfase alfa infusions at home with nursing assistance. Over the course of both studies, all patients experienced ≥1 AE and most patients experienced a drug-related AE, generally of mild or moderate severity. Hypersensitivity reactions reported as related to study drug occurred in 25% of patients. Thirteen patients who chose to receive infusions at home had the same tolerability and safety profile, as well as comparable compliance rates, as patients who chose to receive on-site infusions. All patients developed antibodies to elosulfase alfa. Positivity for neutralizing antibodies was associated with increased drug half-life and decreased drug clearance. Despite formation of antidrug-binding (total antidrug antibodies, TAb) and in vitro neutralizing antibodies (NAb) in all patients, these types of immunogenicity to elosulfase alfa were not correlated with safety or clinical outcomes. In contrast with the reported natural history of Morquio A, no trends toward decreasing endurance, respiratory function, or ability to perform activities of daily living were observed in this cohort over the 5-year period.

8.
J Pediatr Endocrinol Metab ; 31(3): 297-304, 2018 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-29425111

RESUMO

BACKGROUND: Children with long-chain fatty acid ß-oxidation disorders (LCFAOD) presenting with clinical symptoms are treated with a specialist infant formula, with medium chain triglyceride (MCT) mainly replacing long chain triglyceride (LCT). It is essential that the safety and efficacy of any new specialist formula designed for LCFAOD be tested in infants and children. METHODS: In an open-label, 21-day, phase I trial, we studied the safety of a new MCT-based formula (feed 1) in six well-controlled children (three male), aged 7-13 years (median 9 years) with LCFAOD (very long chain acyl CoA dehydrogenase deficiency [VLCADD], n=2; long chain 3-hydroxyacyl CoA dehydrogenase deficiency [LCHADD], n=2; carnitine acyl carnitine translocase deficiency [CACTD], n=2). Feed 1 (Lipistart; Vitaflo) contained 30% energy from MCT, 7.5% LCT and 3% linoleic acid and it was compared with a conventional MCT feed (Monogen; Nutricia) (feed 2) containing 17% energy from MCT, 3% LCT and 1.1% linoleic acid. Subjects consumed feed 2 for 7 days then feed 1 for 7 days and finally resumed feed 2 for 7 days. Vital signs, blood biochemistry, ECG, weight, height, food/feed intake and symptoms were monitored. RESULTS: Five subjects completed the study. Their median daily volume of both feeds was 720 mL (range 500-1900 mL/day). Feed 1 was associated with minimal changes in tolerance, free fatty acids (FFA), acylcarnitines, 3-hydroxybutyrate (3-HB), creatine kinase (CK), blood glucose, liver enzymes and no change in an electrocardiogram (ECG). No child complained of muscle pain or symptoms associated with LCFAOD on either feed. CONCLUSIONS: This is the first safety trial reported of an MCT formula specifically designed for infants and children with LCFAOD. In this short-term study, it appeared safe and well tolerated in this challenging group.


Assuntos
3-Hidroxiacil-CoA Desidrogenases/deficiência , Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Carnitina Aciltransferases/deficiência , Erros Inatos do Metabolismo Lipídico/dietoterapia , Doenças Mitocondriais/dietoterapia , Doenças Musculares/dietoterapia , Triglicerídeos/administração & dosagem , Adolescente , Criança , Feminino , Humanos , Masculino , Triglicerídeos/efeitos adversos
9.
Nutr. hosp ; 35(1): 237-244, ene.-feb. 2018. tab, graf
Artigo em Inglês | IBECS | ID: ibc-172112

RESUMO

Introduction: 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase deficiency is an autosomal recessive disorder that usually presents in the neonatal period with vomiting, metabolic acidosis, hypoglycemia and absent ketonuria. Few cases are reported in the literature, and optimal dietary management and long term outcome are not fully understood. Case report: We report a 2 year old girl with HMG-CoA-lyase deficiency who had limited fasting tolerance on a low protein diet, with several recurrent hospital admissions with severe hypoketotic hypoglycaemia and metabolic acidosis. We also review the dietary management and outcome of other reported cases in the literature. Discussion: In order to define optimal dietary treatment, it is important to collect higher numbers of case studies with detailed dietary management, fasting times and outcome (AU)


Introducción: la deficiencia de la 3-hidroxi-3-metilglutaril-CoA (HMG-CoA) liasa es un desorden autosómico recesivo que normalmente se presenta en la infancia con vómitos, acidosis metabólica, hipoglicemia y sin cetonuria. Se han publicado pocos casos en la literatura científica sobre el mejor tratamiento dietético para el adecuado desarrollo de los pacientes a largo plazo, por lo que esta deficiencia no es bien conocida. Caso clínico: presentamos una niña de 2 años con deficiencia de la 3-hidroxi-3-metilglutaril-CoA (HMG-CoA) liasa. Recibiendo una dieta baja en proteína con una tolerancia de ayuno limitada con episodios recurrentes de admisión hospitalaria con hipoglicemia hipoketotica y acidosis metabólica. También hemos revisado el tratamiento dietético y el desarrollo de otros casos publicados en la literatura científica. Discusión: es importante recoger más casos clínicos describiendo el tratamiento dietético seguido, el tiempo máximo de ayuno y el desarrollo de los pacientes con el objetivo de definir el mejor tratamiento (AU)


Assuntos
Humanos , Feminino , Lactente , Hidroximetilglutaril-CoA Sintase/deficiência , Erros Inatos do Metabolismo/dietoterapia , Cetose/dietoterapia , Leucina/efeitos adversos , Gorduras na Dieta/efeitos adversos , Hipoglicemia/dietoterapia
10.
Mol Genet Metab ; 123(1): 28-42, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29331171

RESUMO

BACKGROUND: Mitochondrial diseases, a group of multi-systemic disorders often characterized by tissue-specific phenotypes, are usually progressive and fatal disorders resulting from defects in oxidative phosphorylation. MTO1 (Mitochondrial tRNA Translation Optimization 1), an evolutionarily conserved protein expressed in high-energy demand tissues has been linked to human early-onset combined oxidative phosphorylation deficiency associated with hypertrophic cardiomyopathy, often referred to as combined oxidative phosphorylation deficiency-10 (COXPD10). MATERIAL AND METHODS: Thirty five cases of MTO1 deficiency were identified and reviewed through international collaboration. The cases of two female siblings, who presented at 1 and 2years of life with seizures, global developmental delay, hypotonia, elevated lactate and complex I and IV deficiency on muscle biopsy but without cardiomyopathy, are presented in detail. RESULTS: For the description of phenotypic features, the denominator varies as the literature was insufficient to allow for complete ascertainment of all data for the 35 cases. An extensive review of all known MTO1 deficiency cases revealed the most common features at presentation to be lactic acidosis (LA) (21/34; 62% cases) and hypertrophic cardiomyopathy (15/34; 44% cases). Eventually lactic acidosis and hypertrophic cardiomyopathy are described in 35/35 (100%) and 27/34 (79%) of patients with MTO1 deficiency, respectively; with global developmental delay/intellectual disability present in 28/29 (97%), feeding difficulties in 17/35 (49%), failure to thrive in 12/35 (34%), seizures in 12/35 (34%), optic atrophy in 11/21 (52%) and ataxia in 7/34 (21%). There are 19 different pathogenic MTO1 variants identified in these 35 cases: one splice-site, 3 frameshift and 15 missense variants. None have bi-allelic variants that completely inactivate MTO1; however, patients where one variant is truncating (i.e. frameshift) while the second one is a missense appear to have a more severe, even fatal, phenotype. These data suggest that complete loss of MTO1 is not viable. A ketogenic diet may have exerted a favourable effect on seizures in 2/5 patients. CONCLUSION: MTO1 deficiency is lethal in some but not all cases, and a genotype-phenotype relation is suggested. Aside from lactic acidosis and cardiomyopathy, developmental delay and other phenotypic features affecting multiple organ systems are often present in these patients, suggesting a broader spectrum than hitherto reported. The diagnosis should be suspected on clinical features and the presence of markers of mitochondrial dysfunction in body fluids, especially low residual complex I, III and IV activity in muscle. Molecular confirmation is required and targeted genomic testing may be the most efficient approach. Although subjective clinical improvement was observed in a small number of patients on therapies such as ketogenic diet and dichloroacetate, no evidence-based effective therapy exists.

11.
Dalton Trans ; 46(39): 13300-13313, 2017 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-28771266

RESUMO

Herein, a bis-amido tris-amine macrocycle and five bipyridine-based bidentate chelating ligands were investigated towards various divalent transition metal ion (NiII, CoII, CuII, and ZnII)-templated syntheses of metallo [2]pseudorotaxanes. The formation of these ternary complexes was elucidated via different spectroscopic techniques such as ESI-MS, absorption spectroscopy, EPR spectroscopy, and single-crystal X-ray diffraction studies wherever possible. Azide-terminated NiII, CoII, CuII, ZnII-templated [2]pseudorotaxanes were explored to generate [2]rotaxane, ROT, via reaction with an alkyne-terminated triphenylene unit as a stopper under the mild reaction condition of the CuI-catalyzed azide-alkyne cycloaddition reaction. NiII-templated [2]pseudorotaxane was found to be the best precursor towards the high-yield synthesis of ROT. The interpenetrative nature of the center piece in metal-free rotaxane was also established through various spectroscopic techniques such as ESI-MS and 1D and 2D (COSY, NOESY, ROESY, and DOSY) NMR spectroscopy. Furthermore, ROT was functionalized via tri-acetylation as AcROT to incorporate three tertiary amides at the tris-amine centers; this AcROT exhibited rotamer-induced molecular motions in an interpenetrated system via the formation of multiple conformers/co-conformers. Additionally, the existence of multiple rotamers was established via variable-temperature NMR spectroscopic studies. Li+ and 12-crown-4 were found to be suitable for the reversible conformation/co-conformation fixation of tri-acetylated bis-amido tris-amine macrocyclic wheel-based rotaxane.

12.
Dalton Trans ; 46(23): 7421-7433, 2017 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-28548179

RESUMO

The threading of 'U' shaped bent axles having diverse functionalities (Axle1-Axle10) is investigated by using a heteroditopic amido-amine macrocyclic (MC) wheel via NiII or CuII metal ion templation. These bent shaped axles are the derivatives of 4,4'-substituted 2,2'-bipyridine, which are composed of various terminal groups like alkene, alkyne, bromide, hydroxyl and azide. Such metallo [2]pseudorotaxanes are well characterised by ESI-MS, EPR and FT-IR spectroscopic studies, UV-Vis absorption studies, elemental analysis and single-crystal X-ray diffraction studies wherever possible. Experimental evidence supports 1 : 1 : 1 ternary complexation between MC, the metal ion and axle. The single crystal X-ray structures of three CuII templated ternary complexes (PR1', PR3' and PR7') show the penta-coordination arrangement around the templating metal ion. Interestingly, judicious selection of chemical functionalities in the complementary wheel and axle components enables to show the existence of various covalent and non-covalent interactions.

13.
J Inherit Metab Dis ; 40(3): 357-368, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28251416

RESUMO

OBJECTIVES: This UK-wide study defines the natural history of argininosuccinic aciduria and compares long-term neurological outcomes in patients presenting clinically or treated prospectively from birth with ammonia-lowering drugs. METHODS: Retrospective analysis of medical records prior to March 2013, then prospective analysis until December 2015. Blinded review of brain MRIs. ASL genotyping. RESULTS: Fifty-six patients were defined as early-onset (n = 23) if symptomatic < 28 days of age, late-onset (n = 23) if symptomatic later, or selectively screened perinatally due to a familial proband (n = 10). The median follow-up was 12.4 years (range 0-53). Long-term outcomes in all groups showed a similar neurological phenotype including developmental delay (48/52), epilepsy (24/52), ataxia (9/52), myopathy-like symptoms (6/52) and abnormal neuroimaging (12/21). Neuroimaging findings included parenchymal infarcts (4/21), focal white matter hyperintensity (4/21), cortical or cerebral atrophy (4/21), nodular heterotopia (2/21) and reduced creatine levels in white matter (4/4). 4/21 adult patients went to mainstream school without the need of additional educational support and 1/21 lives independently. Early-onset patients had more severe involvement of visceral organs including liver, kidney and gut. All early-onset and half of late-onset patients presented with hyperammonaemia. Screened patients had normal ammonia at birth and received treatment preventing severe hyperammonaemia. ASL was sequenced (n = 19) and 20 mutations were found. Plasma argininosuccinate was higher in early-onset compared to late-onset patients. CONCLUSIONS: Our study further defines the natural history of argininosuccinic aciduria and genotype-phenotype correlations. The neurological phenotype does not correlate with the severity of hyperammonaemia and plasma argininosuccinic acid levels. The disturbance in nitric oxide synthesis may be a contributor to the neurological disease. Clinical trials providing nitric oxide to the brain merit consideration.


Assuntos
Acidúria Argininossuccínica/patologia , Acidúria Argininossuccínica/terapia , Adolescente , Adulto , Amônia/metabolismo , Ácido Argininossuccínico/sangue , Acidúria Argininossuccínica/sangue , Acidúria Argininossuccínica/genética , Criança , Pré-Escolar , Feminino , Seguimentos , Genótipo , Humanos , Hiperamonemia/metabolismo , Hiperamonemia/patologia , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Mutação/genética , Fenótipo , Estudos Prospectivos , Estudos Retrospectivos , Adulto Jovem
14.
Mol Genet Metab ; 120(4): 337-341, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28216384

RESUMO

Clinical and laboratory data were collected from three Finnish patients including a sibling pair and another unrelated child with unexplained childhood hypoglycemia. Transient elevation of alanine transaminase, lactate and tricarboxylic acid cycle intermediates, especially fumarate, were noticed in urine organic acid analysis. Exome sequencing was performed for the patients and their parents. A novel homozygous PCK1 c.925G>A (p.G309R) mutation was detected in all affected individuals. COS-1 cells transfected with mutant PCK1 transcripts were used to study the pathogenic nature of the detected variant. The COS-1 transfected cells showed the mutant gene to be incapable of producing a normally functioning cytosolic phosphoenolpyruvate carboxykinase (PEPCK) enzyme. This report further delineates the clinical phenotype of isolated cytosolic PEPCK deficiency and offers a metabolic pattern helping to recognize these patients. Cytosolic PEPCK deficiency should be considered in the differential diagnosis of children presenting with hypoglycemia, hepatic dysfunction and elevated tricarboxylic acid intermediates in urinary organic acid analysis.


Assuntos
Erros Inatos do Metabolismo dos Carboidratos/diagnóstico , Hipoglicemia/etiologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Hepatopatias/diagnóstico , Fígado/fisiopatologia , Mutação de Sentido Incorreto , Fosfoenolpiruvato Carboxiquinase (GTP)/deficiência , Urina/química , Animais , Células COS , Erros Inatos do Metabolismo dos Carboidratos/fisiopatologia , Cercopithecus aethiops , Criança , Exoma , Feminino , Predisposição Genética para Doença , Homozigoto , Humanos , Hepatopatias/fisiopatologia , Masculino , Linhagem , Fosfoenolpiruvato Carboxiquinase (GTP)/genética , Análise de Sequência de DNA/métodos
15.
J Inherit Metab Dis ; 40(1): 49-74, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27778219

RESUMO

Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to accumulation of homocysteine. Patients can present to many different specialists and diagnosis is often delayed. Severely affected patients usually present in childhood with ectopia lentis, learning difficulties and skeletal abnormalities. These patients generally require treatment with a low-methionine diet and/or betaine. In contrast, mildly affected patients are likely to present as adults with thromboembolism and to respond to treatment with pyridoxine. In this article, we present recommendations for the diagnosis and management of CBS deficiency, based on a systematic review of the literature. Unfortunately, the quality of the evidence is poor, as it often is for rare diseases. We strongly recommend measuring the plasma total homocysteine concentrations in any patient whose clinical features suggest the diagnosis. Our recommendations may help to standardise testing for pyridoxine responsiveness. Current evidence suggests that patients are unlikely to develop complications if the plasma total homocysteine concentration is maintained below 120 µmol/L. Nevertheless, we recommend keeping the concentration below 100 µmol/L because levels fluctuate and the complications associated with high levels are so serious.


Assuntos
Cistationina beta-Sintase/deficiência , Homocistinúria/dietoterapia , Homocistinúria/tratamento farmacológico , Betaína/metabolismo , Homocisteína/metabolismo , Humanos , Metionina/metabolismo , Piridoxina/uso terapêutico
16.
J Pediatr Gastroenterol Nutr ; 63(6): 592-597, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27482763

RESUMO

BACKGROUND: Mitochondrial liver disease (MLD), and in particular mitochondrial DNA (mtDNA) depletion syndrome (MDS) is an important cause of acute liver failure (ALF) in infancy. Early and accurate diagnosis is important because liver transplantation (LT) is often contraindicated. It is unclear which methods are the best to diagnose MLD in the setting of ALF. OBJECTIVE: The aim of the study was to determine the incidence of MLD in children younger than 2 years with ALF and the utility of routine investigations to detect MLD. METHODS: Thirty-nine consecutive infants with ALF were admitted to a single unit from 2009 to 2011. All were extensively investigated using an established protocol. Genes implicated in mitochondrial DNA depletion syndrome were sequenced in all cases and tissue mtDNA copy number measured where available. RESULTS: Five infants (17%) had genetically proven MLD: DGUOK (n = 2), POLG (n = 2), and MPV17 (1). Four of these died, whereas 1 recovered. Two had normal muscle mtDNA copy number and 3 had normal muscle respiratory chain enzymes. An additional 8 children had low hepatic mtDNA copy number but pathogenic mutations were not detected. One of these developed fatal multisystemic disease after LT, whereas 5 who survived remain well without evidence of multisystemic disease up to 6 years later. Magnetic resonance spectroscopy did not distinguish between those with and without MLD. CONCLUSIONS: Low liver mtDNA copy number may be a secondary phenomenon in ALF.Screening for mtDNA maintenance gene mutations may be the most efficient way to confirm MLD in ALF in the first 2 years of life.


Assuntos
DNA Mitocondrial/genética , Falência Hepática Aguda/etiologia , Doenças Mitocondriais/complicações , Doenças Mitocondriais/genética , Feminino , Humanos , Lactente , Recém-Nascido , Pseudo-Obstrução Intestinal , Fígado/diagnóstico por imagem , Imagem por Ressonância Magnética , Masculino , Doenças Mitocondriais/diagnóstico , Encefalomiopatias Mitocondriais , Mutação
17.
J Med Genet ; 53(11): 768-775, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27412952

RESUMO

BACKGROUND: Mutations in the RMND1 (Required for Meiotic Nuclear Division protein 1) gene have recently been linked to infantile onset mitochondrial disease characterised by multiple mitochondrial respiratory chain defects. METHODS: We summarised the clinical, biochemical and molecular genetic investigation of an international cohort of affected individuals with RMND1 mutations. In addition, we reviewed all the previously published cases to determine the genotype-phenotype correlates and performed survival analysis to identify prognostic factors. RESULTS: We identified 14 new cases from 11 pedigrees that harbour recessive RMND1 mutations, including 6 novel variants: c.533C>A, p.(Thr178Lys); c.565C>T, p.(Gln189*); c.631G>A, p.(Val211Met); c.1303C>T, p.(Leu435Phe); c.830+1G>A and c.1317+1G>T. Together with all previously published cases (n=32), we show that congenital sensorineural deafness, hypotonia, developmental delay and lactic acidaemia are common clinical manifestations with disease onset under 2 years. Renal involvement is more prevalent than seizures (66% vs 44%). In addition, median survival time was longer in patients with renal involvement compared with those without renal disease (6 years vs 8 months, p=0.009). The neurological phenotype also appears milder in patients with renal involvement. CONCLUSIONS: The clinical phenotypes and prognosis associated with RMND1 mutations are more heterogeneous than that were initially described. Regular monitoring of kidney function is imperative in the clinical practice in light of nephropathy being present in over 60% of cases. Furthermore, renal replacement therapy should be considered particularly in those patients with mild neurological manifestation as shown in our study that four recipients of kidney transplant demonstrate good clinical outcome to date.

18.
N Engl J Med ; 374(23): 2246-55, 2016 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-27276562

RESUMO

BACKGROUND: Whole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level. METHODS: To uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient's clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes. RESULTS: We performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 probands had been born to predominantly nonconsanguineous parents of European descent. In 37 probands, we identified variants in 2 genes newly implicated in disease, 9 candidate genes, 22 known genes with newly identified phenotypes, and 9 genes with expected phenotypes; in most of the genes, the variants were classified as either pathogenic or probably pathogenic. Complex phenotypes of patients in five families were explained by coexisting monogenic conditions. We obtained a diagnosis in 28 of 41 probands (68%) who were evaluated. A test of a targeted intervention was performed in 18 patients (44%). CONCLUSIONS: Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%. (Funded by BC Children's Hospital Foundation and others.).


Assuntos
Exoma , Testes Genéticos/métodos , Erros Inatos do Metabolismo/genética , Análise de Sequência de DNA/métodos , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Genótipo , Humanos , Lactente , Deficiência Intelectual/genética , Masculino , Erros Inatos do Metabolismo/diagnóstico , Fenótipo , Adulto Jovem
19.
Mol Genet Metab ; 118(1): 21-7, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26971250

RESUMO

We report a patient from a consanguineous family who presented with transient acute liver failure and biochemical patterns suggestive of disturbed urea cycle and mitochondrial function, for whom conventional genetic and metabolic investigations for acute liver failure failed to yield a diagnosis. Whole exome sequencing revealed a homozygous 12-bp deletion in PCK1 (MIM 614168) encoding cytosolic phosphoenolpyruvate carboxykinase (PEPCK); enzymatic studies subsequently confirmed its pathogenic nature. We propose that PEPCK deficiency should be considered in the young child with unexplained liver failure, especially where there are marked, accumulations of TCA cycle metabolites on urine organic acid analysis and/or an amino acid profile with hyperammonaemia suggestive of a proximal urea cycle defect during the acute episode. If suspected, intravenous administration of dextrose should be initiated. Long-term management comprising avoidance of fasting with the provision of a glucose polymer emergency regimen for illness management may be sufficient to prevent future episodes of liver failure. This case report provides further insights into the (patho-)physiology of energy metabolism, confirming the power of genomic analysis of unexplained biochemical phenotypes.


Assuntos
Sequência de Bases , Erros Inatos do Metabolismo dos Carboidratos/diagnóstico , Gastroenterite/etiologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Hepatopatias/diagnóstico , Falência Hepática Aguda/etiologia , Fosfoenolpiruvato Carboxiquinase (GTP)/deficiência , Deleção de Sequência , Erros Inatos do Metabolismo dos Carboidratos/tratamento farmacológico , Erros Inatos do Metabolismo dos Carboidratos/genética , Consanguinidade , Exoma , Gastroenterite/genética , Glucose/administração & dosagem , Glucose/uso terapêutico , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Hepatopatias/tratamento farmacológico , Hepatopatias/genética , Falência Hepática Aguda/genética , Masculino , Linhagem , Fosfoenolpiruvato Carboxiquinase (GTP)/genética
20.
Genet Med ; 18(10): 991-1000, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-26913920

RESUMO

PURPOSE: Four mitochondrial metabolic liver enzymes require bicarbonate, which is provided by the carbonic anhydrase isoforms VA (CAVA) and VB (CAVB). Defective hepatic bicarbonate production leads to a unique combination of biochemical findings: hyperammonemia, elevated lactate and ketone bodies, metabolic acidosis, hypoglycemia, and excretion of carboxylase substrates. This study aimed to test for CAVA or CAVB deficiencies in a group of 96 patients with early-onset hyperammonemia and to prove the disease-causing role of the CAVA variants found. METHODS: We performed CA5A and CA5B sequencing in the described cohort and developed an expression system using insect cells, which enabled the characterization of wild-type CAVA, clinical mutations, and three variants that affect functional residues. RESULTS: In 10 of 96 patients, mutations in CA5A were identified on both alleles but none in CA5B. Exhibiting decreased enzyme activity or thermal stability, all CAVA mutations were proven to cause disease, whereas the three variants showed no relevant effect. CONCLUSION: CAVA deficiency is a differential diagnosis of early-onset and life-threatening metabolic crisis, with hyperammonemia, hyperlactatemia, and ketonuria as apparently obligate signs. It seems to be more common than other rare metabolic diseases, and early identification may allow specific treatment of hyperammonemia and ultimately prevent neurologic sequelae.Genet Med 18 10, 991-1000.


Assuntos
Acidose/genética , Anidrases Carbônicas/genética , Hiperamonemia/genética , Fígado/metabolismo , Acidose/metabolismo , Acidose/patologia , Adolescente , Bicarbonatos/metabolismo , Anidrases Carbônicas/deficiência , Anidrases Carbônicas/metabolismo , Criança , Pré-Escolar , Humanos , Hiperamonemia/metabolismo , Hiperamonemia/patologia , Hipoglicemia/genética , Hipoglicemia/metabolismo , Hipoglicemia/patologia , Lactente , Recém-Nascido , Ácido Láctico/metabolismo , Fígado/enzimologia , Fígado/patologia , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Mutação , Isoformas de Proteínas
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