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1.
J Inherit Metab Dis ; 42(3): 424-437, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30873612

RESUMO

STUDY OBJECTIVE: A phase 1/2 clinical trial was performed in individuals with cystathionine ß synthase (CBS) deficient homocystinuria with aims to: (a) assess pharmacokinetics and safety of taurine therapy, (b) evaluate oxidative stress, inflammation, and vascular function in CBS deficiency, and (c) evaluate the impact of short-term taurine treatment. METHODS: Individuals with pyridoxine-nonresponsive CBS deficiency with homocysteine >50 µM, without inflammatory disorder or on antioxidant therapy were enrolled. Biomarkers of oxidative stress and inflammation, endothelial function (brachial artery flow-mediated dilation [FMD]), and disease-related metabolites obtained at baseline were compared to normal values. While maintaining current treatment, patients were treated with 75 mg/kg taurine twice daily, and treatment response assessed after 4 hours and 4 days. RESULTS: Fourteen patients (8-35 years; 8 males, 6 females) were enrolled with baseline homocysteine levels 161 ± 67 µM. The study found high-dose taurine to be safe when excluding preexisting hypertriglyceridemia. Taurine pharmacokinetics showed a rapid peak level returning to near normal levels at 12 hours, but had slow accumulation and elevated predosing levels after 4 days of treatment. Only a single parameter of oxidative stress, 2,3-dinor-8-isoprostaglandin-F2α, was elevated at baseline, with no elevated inflammatory parameters, and no change in FMD values overall. Taurine had no effect on any of these parameters. However, the effect of taurine was strongly related to pretreatment FMD values; and taurine significantly improved FMD in the subset of individuals with pretreatment FMD values <10% and in individuals with homocysteine levels >125 µM, pertinent to endothelial function. CONCLUSION: Taurine improves endothelial function in CBS-deficient homocystinuria in patients with preexisting reduced function.

2.
J Inherit Metab Dis ; 42(3): 565-574, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30663059

RESUMO

Pyridoxine-dependent epilepsy (PDE) is often characterized as an early onset epileptic encephalopathy with dramatic clinical improvement following pyridoxine supplementation. Unfortunately, not all patients present with classic neonatal seizures or respond to an initial pyridoxine trial, which can result in the under diagnosis of this treatable disorder. Restriction of lysine intake and transport is associated with improved neurologic outcomes, although treatment should be started in the first year of life to be effective. Because of the documented diagnostic delay and benefit of early treatment, we aimed to develop a newborn screening method for PDE. Previous studies have demonstrated the accumulation of Δ1 -piperideine-6-carboxylate and α-aminoadipic semialdehyde in individuals with PDE, although these metabolites are unstable at room temperature (RT) limiting their utility for newborn screening. As a result, we sought to identify a biomarker that could be applied to current newborn screening paradigms. We identified a novel metabolite, 6-oxo-pipecolate (6-oxo-PIP), which accumulates in substantial amounts in blood, plasma, urine, and cerebral spinal fluid of individuals with PDE. Using a stable isotope-labeled internal standard, we developed a nonderivatized liquid chromatography tandem mass spectrometry-based method to quantify 6-oxo-PIP. This method replicates the analytical techniques used in many laboratories and could be used with few modifications in newborn screening programs. Furthermore, 6-oxo-PIP was measurable in urine for 4 months even when stored at RT. Herein, we report a novel biomarker for PDE that is stable at RT and can be quantified using current newborn screening techniques.

3.
Nat Commun ; 9(1): 4065, 2018 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-30283131

RESUMO

Mitochondrial protein synthesis requires charging mt-tRNAs with their cognate amino acids by mitochondrial aminoacyl-tRNA synthetases, with the exception of glutaminyl mt-tRNA (mt-tRNAGln). mt-tRNAGln is indirectly charged by a transamidation reaction involving the GatCAB aminoacyl-tRNA amidotransferase complex. Defects involving the mitochondrial protein synthesis machinery cause a broad spectrum of disorders, with often fatal outcome. Here, we describe nine patients from five families with genetic defects in a GatCAB complex subunit, including QRSL1, GATB, and GATC, each showing a lethal metabolic cardiomyopathy syndrome. Functional studies reveal combined respiratory chain enzyme deficiencies and mitochondrial dysfunction. Aminoacylation of mt-tRNAGln and mitochondrial protein translation are deficient in patients' fibroblasts cultured in the absence of glutamine but restore in high glutamine. Lentiviral rescue experiments and modeling in S. cerevisiae homologs confirm pathogenicity. Our study completes a decade of investigations on mitochondrial aminoacylation disorders, starting with DARS2 and ending with the GatCAB complex.

4.
Am J Hum Genet ; 102(4): 557-573, 2018 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-29576218

RESUMO

Mitochondrial disorders causing neurodegeneration in childhood are genetically heterogeneous, and the underlying genetic etiology remains unknown in many affected individuals. We identified biallelic variants in PMPCB in individuals of four families including one family with two affected siblings with neurodegeneration and cerebellar atrophy. PMPCB encodes the catalytic subunit of the essential mitochondrial processing protease (MPP), which is required for maturation of the majority of mitochondrial precursor proteins. Mitochondria isolated from two fibroblast cell lines and induced pluripotent stem cells derived from one affected individual and differentiated neuroepithelial stem cells showed reduced PMPCB levels and accumulation of the processing intermediate of frataxin, a sensitive substrate for MPP dysfunction. Introduction of the identified PMPCB variants into the homologous S. cerevisiae Mas1 protein resulted in a severe growth and MPP processing defect leading to the accumulation of mitochondrial precursor proteins and early impairment of the biogenesis of iron-sulfur clusters, which are indispensable for a broad range of crucial cellular functions. Analysis of biopsy materials of an affected individual revealed changes and decreased activity in iron-sulfur cluster-containing respiratory chain complexes and dysfunction of mitochondrial and cytosolic Fe-S cluster-dependent enzymes. We conclude that biallelic mutations in PMPCB cause defects in MPP proteolytic activity leading to dysregulation of iron-sulfur cluster biogenesis and triggering a complex neurological phenotype of neurodegeneration in early childhood.

5.
Am J Hum Genet ; 102(3): 494-504, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29478781

RESUMO

ATP synthase, H+ transporting, mitochondrial F1 complex, δ subunit (ATP5F1D; formerly ATP5D) is a subunit of mitochondrial ATP synthase and plays an important role in coupling proton translocation and ATP production. Here, we describe two individuals, each with homozygous missense variants in ATP5F1D, who presented with episodic lethargy, metabolic acidosis, 3-methylglutaconic aciduria, and hyperammonemia. Subject 1, homozygous for c.245C>T (p.Pro82Leu), presented with recurrent metabolic decompensation starting in the neonatal period, and subject 2, homozygous for c.317T>G (p.Val106Gly), presented with acute encephalopathy in childhood. Cultured skin fibroblasts from these individuals exhibited impaired assembly of F1FO ATP synthase and subsequent reduced complex V activity. Cells from subject 1 also exhibited a significant decrease in mitochondrial cristae. Knockdown of Drosophila ATPsynδ, the ATP5F1D homolog, in developing eyes and brains caused a near complete loss of the fly head, a phenotype that was fully rescued by wild-type human ATP5F1D. In contrast, expression of the ATP5F1D c.245C>T and c.317T>G variants rescued the head-size phenotype but recapitulated the eye and antennae defects seen in other genetic models of mitochondrial oxidative phosphorylation deficiency. Our data establish c.245C>T (p.Pro82Leu) and c.317T>G (p.Val106Gly) in ATP5F1D as pathogenic variants leading to a Mendelian mitochondrial disease featuring episodic metabolic decompensation.

6.
Pediatr Neurol ; 71: 65-69, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28363510

RESUMO

BACKGROUND: Autosomal recessive or X-linked inborn errors of intracellular cobalamin metabolism can lead to methylmalonic aciduria and homocystinuria. In neonates, both increased cerebrospinal fluid glycine and cerebrospinal fluid/plasma glycine ratio are biochemical features of nonketotic hyperglycinemia. METHODS: We describe a boy presenting in the neonatal period with hypotonia, tonic, clonic, and later myoclonic seizures, subsequently evolving into refractory epilepsy and severe neurocognitive impairment. RESULTS: Increased cerebrospinal fluid glycine and cerebrospinal fluid to plasma glycine ratio were indicative of nonketotic hyperglycinemia. Early magnetic resonance imaging showed restricted diffusion and decreased apparent diffusion coefficient values in posterior limb of internal capsules and later in entire internal capsules and posterior white matter. Sequencing did not show a mutation in AMT, GLDC, or GCSH. Biochemical analysis identified persistently increased cerebrospinal fluid levels of glycine and methylmalonic acid and increased urinary methylmalonic acid and plasma homocysteine levels, which improved on higher parenteral hydroxocobalamin dose. Exome sequencing identified a known pathogenic sequence variant in X-linked cobalamin (HCFC1), c.344C>T, p. Ala115Val. In addition, a hemizygous mutation was found in the ATRX (c. 2728A>G, p. Lys910Glu). Retrospective review of two other patients with X-linked cobalamin deficiency also identified increased cerebrospinal fluid glycine levels. CONCLUSIONS: This boy had X-linked cobalamin deficiency (HCFC1) with increased cerebrospinal fluid glycine and methylmalonic acid and increased cerebrospinal fluid to plasma glycine ratio suggesting a brain hyperglycinemia. Putative binding sites for HCFC1 and its binding partner THAP11 were identified near genes of the glycine cleavage enzyme, providing a potential mechanistic link between HCFC1 mutations and increased glycine.


Assuntos
Doenças Genéticas Ligadas ao Cromossomo X/líquido cefalorraquidiano , Glicina/líquido cefalorraquidiano , Hiperglicinemia não Cetótica/diagnóstico , Ácido Metilmalônico/líquido cefalorraquidiano , Deficiência de Vitamina B 12/líquido cefalorraquidiano , Deficiência de Vitamina B 12/diagnóstico , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Biomarcadores/urina , Encéfalo/diagnóstico por imagem , Diagnóstico Diferencial , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças Genéticas Ligadas ao Cromossomo X/terapia , Glicina/sangue , Humanos , Recém-Nascido , Masculino , Deficiência de Vitamina B 12/tratamento farmacológico , Deficiência de Vitamina B 12/genética
7.
Mitochondrion ; 34: 84-90, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28216230

RESUMO

We report the clinical, biochemical, and molecular findings in two brothers with encephalopathy and multi-systemic disease. Abnormal transferrin glycoforms were suggestive of a type I congenital disorder of glycosylation (CDG). While exome sequencing was negative for CDG related candidate genes, the testing revealed compound heterozygous mutations in the mitochondrial elongation factor G gene (GFM1). One of the mutations had been reported previously while the second, novel variant was found deep in intron 6, activating a cryptic splice site. Functional studies demonstrated decreased GFM1 protein levels, suggested disrupted assembly of mitochondrial complexes III and V and decreased activities of mitochondrial complexes I and IV, all indicating combined OXPHOS deficiency.


Assuntos
Anormalidades Congênitas/genética , Anormalidades Congênitas/patologia , Expressão Gênica , Proteínas Mitocondriais/biossíntese , Proteínas Mitocondriais/genética , Fosforilação Oxidativa , Fator G para Elongação de Peptídeos/biossíntese , Fator G para Elongação de Peptídeos/genética , Sítios de Splice de RNA , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Masculino
8.
Hum Mol Genet ; 26(4): 702-716, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-28040730

RESUMO

An infant presented with fatal infantile lactic acidosis and cardiomyopathy, and was found to have profoundly decreased activity of respiratory chain complex I in muscle, heart and liver. Exome sequencing revealed compound heterozygous mutations in NDUFB10, which encodes an accessory subunit located within the PD part of complex I. One mutation resulted in a premature stop codon and absent protein, while the second mutation replaced the highly conserved cysteine 107 with a serine residue. Protein expression of NDUFB10 was decreased in muscle and heart, and less so in the liver and fibroblasts, resulting in the perturbed assembly of the holoenzyme at the 830 kDa stage. NDUFB10 was identified together with three other complex I subunits as a substrate of the intermembrane space oxidoreductase CHCHD4 (also known as Mia40). We found that during its mitochondrial import and maturation NDUFB10 transiently interacts with CHCHD4 and acquires disulfide bonds. The mutation of cysteine residue 107 in NDUFB10 impaired oxidation and efficient mitochondrial accumulation of the protein and resulted in degradation of non-imported precursors. Our findings indicate that mutations in NDUFB10 are a novel cause of complex I deficiency associated with a late stage assembly defect and emphasize the role of intermembrane space proteins for the efficient assembly of complex I.

9.
Free Radic Biol Med ; 92: 141-151, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26773591

RESUMO

A novel rat model for a well-characterized human mitochondrial disease, mitochondrial DNA depletion syndrome with associated deoxyguanosine kinase (DGUOK) deficiency, is described. The rat model recapitulates the pathologic and biochemical signatures of the human disease. The application of electron paramagnetic (spin) resonance (EPR) spectroscopy to the identification and characterization of respiratory chain abnormalities in the mitochondria from freshly frozen tissue of the mitochondrial disease model rat is introduced. EPR is shown to be a sensitive technique for detecting mitochondrial functional abnormalities in situ and, here, is particularly useful in characterizing the redox state changes and oxidative stress that can result from depressed expression and/or diminished specific activity of the distinct respiratory chain complexes. As EPR requires no sample preparation or non-physiological reagents, it provides information on the status of the mitochondrion as it was in the functioning state. On its own, this information is of use in identifying respiratory chain dysfunction; in conjunction with other techniques, the information from EPR shows how the respiratory chain is affected at the molecular level by the dysfunction. It is proposed that EPR has a role in mechanistic pathophysiological studies of mitochondrial disease and could be used to study the impact of new treatment modalities or as an additional diagnostic tool.


Assuntos
Espectroscopia de Ressonância de Spin Eletrônica , Pseudo-Obstrução Intestinal/diagnóstico , Mitocôndrias/patologia , Doenças Mitocondriais/diagnóstico , Encefalomiopatias Mitocondriais/diagnóstico , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Animais , DNA Mitocondrial/genética , Modelos Animais de Doenças , Transporte de Elétrons/genética , Humanos , Pseudo-Obstrução Intestinal/metabolismo , Pseudo-Obstrução Intestinal/patologia , Mitocôndrias/metabolismo , Doenças Mitocondriais/genética , Doenças Mitocondriais/metabolismo , Doenças Mitocondriais/patologia , Encefalomiopatias Mitocondriais/metabolismo , Encefalomiopatias Mitocondriais/patologia , Oxirredução , Estresse Oxidativo/genética , Fosfotransferases (Aceptor do Grupo Álcool)/isolamento & purificação , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Ratos
10.
J Pediatr ; 170: 234-9, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26749113

RESUMO

OBJECTIVE: To evaluate the impact of sodium benzoate and dextromethorphan treatment on patients with the attenuated form of nonketotic hyperglycinemia. STUDY DESIGN: Families were recruited with 2 siblings both affected with attenuated nonketotic hyperglycinemia. Genetic mutations were expressed to identify residual activity. The outcome on developmental progress and seizures was compared between the first child diagnosed and treated late with the second child diagnosed at birth and treated aggressively from the newborn period using dextromethorphan and benzoate at dosing sufficient to normalize plasma glycine levels. Both siblings were evaluated with similar standardized neurodevelopmental measures. RESULTS: In each sibling set, the second sibling treated from the neonatal period achieved earlier and more developmental milestones, and had a higher developmental quotient. In 3 of the 4 sibling pairs, the younger sibling had no seizures whereas the first child had a seizure disorder. The adaptive behavior subdomains of socialization and daily living skills improved more than motor skills and communication. CONCLUSIONS: Early treatment with dextromethorphan and sodium benzoate sufficient to normalize plasma glycine levels is effective at improving outcome if used in children with attenuated disease with mutations providing residual activity and when started from the neonatal period.


Assuntos
Desenvolvimento Infantil , Dextrometorfano/uso terapêutico , Antagonistas de Aminoácidos Excitatórios/uso terapêutico , Hiperglicinemia não Cetótica/tratamento farmacológico , Irmãos , Benzoato de Sódio/uso terapêutico , Tempo para o Tratamento , Criança , Pré-Escolar , Colorado , Diagnóstico Tardio , Diagnóstico Precoce , Epilepsia/etiologia , Feminino , Humanos , Hiperglicinemia não Cetótica/diagnóstico , Hiperglicinemia não Cetótica/genética , Lactente , Recém-Nascido , Testes de Inteligência , Masculino , Testes Neuropsicológicos
11.
Orphanet J Rare Dis ; 10: 79, 2015 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-26081110

RESUMO

BACKGROUND: Short-chain enoyl-CoA hydratase (SCEH, encoded by ECHS1) catalyzes hydration of 2-trans-enoyl-CoAs to 3(S)-hydroxy-acyl-CoAs. SCEH has a broad substrate specificity and is believed to play an important role in mitochondrial fatty acid oxidation and in the metabolism of branched-chain amino acids. Recently, the first patients with SCEH deficiency have been reported revealing only a defect in valine catabolism. We investigated the role of SCEH in fatty acid and branched-chain amino acid metabolism in four newly identified patients. In addition, because of the Leigh-like presentation, we studied enzymes involved in bioenergetics. METHODS: Metabolite, enzymatic, protein and genetic analyses were performed in four patients, including two siblings. Palmitate loading studies in fibroblasts were performed to study mitochondrial ß-oxidation. In addition, enoyl-CoA hydratase activity was measured with crotonyl-CoA, methacrylyl-CoA, tiglyl-CoA and 3-methylcrotonyl-CoA both in fibroblasts and liver to further study the role of SCEH in different metabolic pathways. Analyses of pyruvate dehydrogenase and respiratory chain complexes were performed in multiple tissues of two patients. RESULTS: All patients were either homozygous or compound heterozygous for mutations in the ECHS1 gene, had markedly reduced SCEH enzymatic activity and protein level in fibroblasts. All patients presented with lactic acidosis. The first two patients presented with vacuolating leukoencephalopathy and basal ganglia abnormalities. The third patient showed a slow neurodegenerative condition with global brain atrophy and the fourth patient showed Leigh-like lesions with a single episode of metabolic acidosis. Clinical picture and metabolite analysis were not consistent with a mitochondrial fatty acid oxidation disorder, which was supported by the normal palmitate loading test in fibroblasts. Patient fibroblasts displayed deficient hydratase activity with different substrates tested. Pyruvate dehydrogenase activity was markedly reduced in particular in muscle from the most severely affected patients, which was caused by reduced expression of E2 protein, whereas E2 mRNA was increased. CONCLUSIONS: Despite its activity towards substrates from different metabolic pathways, SCEH appears to be only crucial in valine metabolism, but not in isoleucine metabolism, and only of limited importance for mitochondrial fatty acid oxidation. In severely affected patients SCEH deficiency can cause a secondary pyruvate dehydrogenase deficiency contributing to the clinical presentation.


Assuntos
Acil Coenzima A/genética , Acil Coenzima A/deficiência , Criança , Enoil-CoA Hidratase/genética , Feminino , Heterozigoto , Humanos , Lactente , Recém-Nascido , Doença de Leigh/diagnóstico , Doença de Leigh/etiologia , Doença de Leigh/genética , Masculino , Mutação
12.
J Med Genet ; 52(8): 532-40, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25787132

RESUMO

BACKGROUND: Mitochondrial disease is often suspected in cases of severe epileptic encephalopathy especially when a complex movement disorder, liver involvement and progressive developmental regression are present. Although mutations in either mitochondrial DNA or POLG are often present, other nuclear defects in mitochondrial DNA replication and protein translation have been associated with a severe epileptic encephalopathy. METHODS AND RESULTS: We identified a proband with an epileptic encephalopathy, complex movement disorder and a combined mitochondrial respiratory chain enzyme deficiency. The child presented with neurological regression, complex movement disorder and intractable seizures. A combined deficiency of mitochondrial complexes I, III and IV was noted in liver tissue, along with increased mitochondrial DNA content in skeletal muscle. Incomplete assembly of complex V, using blue native polyacrylamide gel electrophoretic analysis and complex I, using western blotting, suggested a disorder of mitochondrial transcription or translation. Exome sequencing identified compound heterozygous mutations in CARS2, a mitochondrial aminoacyl-tRNA synthetase. Both mutations affect highly conserved amino acids located within the functional ligase domain of the cysteinyl-tRNA synthase. A specific decrease in the amount of charged mt-tRNA(Cys) was detected in patient fibroblasts compared with controls. Retroviral transfection of the wild-type CARS2 into patient skin fibroblasts led to the correction of the incomplete assembly of complex V, providing functional evidence for the role of CARS2 mutations in disease aetiology. CONCLUSIONS: Our findings indicate that mutations in CARS2 result in a mitochondrial translational defect as seen in individuals with mitochondrial epileptic encephalopathy.


Assuntos
Aminoacil-tRNA Sintetases/genética , Encefalopatias/genética , Epilepsia/genética , Sequência de Aminoácidos , Aminoacilação , Criança , Análise Mutacional de DNA , Exoma , Humanos , Masculino , Dados de Sequência Molecular , RNA de Transferência/metabolismo , Alinhamento de Sequência
13.
Mitochondrion ; 21: 1-10, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25575635

RESUMO

Muscle, heart and liver were analyzed in a male subject who succumbed to HSD10 disease. Respiratory chain enzyme analysis and BN-PAGE showed reduced activities and assembly of complexes I, III, IV, and V. The mRNAs of all RNase P subunits were preserved in heart and overexpressed in muscle, but MRPP2 protein was severely decreased. RNase P upregulation correlated with increased expression of mitochondrial biogenesis factors and preserved mitochondrial enzymes in muscle, but not in heart where this compensatory mechanism was incomplete. We demonstrate elevated amounts of unprocessed pre-tRNAs and mRNA transcripts encoding mitochondrial subunits indicating deficient RNase P activity. This study provides evidence of abnormal mitochondrial RNA processing causing mitochondrial energy failure in HSD10 disease.


Assuntos
3-Hidroxiacil-CoA Desidrogenases/metabolismo , Acetil-CoA C-Acetiltransferase/deficiência , DNA Mitocondrial/metabolismo , Metabolismo Energético , Erros Inatos do Metabolismo Lipídico/fisiopatologia , Mitocôndrias/fisiologia , Transcrição Genética , 3-Hidroxiacil-CoA Desidrogenases/genética , Respiração Celular , Discinesias , Transporte de Elétrons , Expressão Gênica , Humanos , Lactente , Recém-Nascido , Fígado/patologia , Masculino , Retardo Mental Ligado ao Cromossomo X , Mitocôndrias/genética , Músculos/patologia , Miocárdio/patologia , Processamento Pós-Transcricional do RNA
14.
Brain ; 137(Pt 2): 366-79, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24334290

RESUMO

Patients with nonketotic hyperglycinemia and deficient glycine cleavage enzyme activity, but without mutations in AMT, GLDC or GCSH, the genes encoding its constituent proteins, constitute a clinical group which we call 'variant nonketotic hyperglycinemia'. We hypothesize that in some patients the aetiology involves genetic mutations that result in a deficiency of the cofactor lipoate, and sequenced genes involved in lipoate synthesis and iron-sulphur cluster biogenesis. Of 11 individuals identified with variant nonketotic hyperglycinemia, we were able to determine the genetic aetiology in eight patients and delineate the clinical and biochemical phenotypes. Mutations were identified in the genes for lipoate synthase (LIAS), BolA type 3 (BOLA3), and a novel gene glutaredoxin 5 (GLRX5). Patients with GLRX5-associated variant nonketotic hyperglycinemia had normal development with childhood-onset spastic paraplegia, spinal lesion, and optic atrophy. Clinical features of BOLA3-associated variant nonketotic hyperglycinemia include severe neurodegeneration after a period of normal development. Additional features include leukodystrophy, cardiomyopathy and optic atrophy. Patients with lipoate synthase-deficient variant nonketotic hyperglycinemia varied in severity from mild static encephalopathy to Leigh disease and cortical involvement. All patients had high serum and borderline elevated cerebrospinal fluid glycine and cerebrospinal fluid:plasma glycine ratio, and deficient glycine cleavage enzyme activity. They had low pyruvate dehydrogenase enzyme activity but most did not have lactic acidosis. Patients were deficient in lipoylation of mitochondrial proteins. There were minimal and inconsistent changes in cellular iron handling, and respiratory chain activity was unaffected. Identified mutations were phylogenetically conserved, and transfection with native genes corrected the biochemical deficiency proving pathogenicity. Treatments of cells with lipoate and with mitochondrially-targeted lipoate were unsuccessful at correcting the deficiency. The recognition of variant nonketotic hyperglycinemia is important for physicians evaluating patients with abnormalities in glycine as this will affect the genetic causation and genetic counselling, and provide prognostic information on the expected phenotypic course.


Assuntos
Variação Genética/genética , Glutarredoxinas/genética , Hiperglicinemia não Cetótica/genética , Mutação/genética , Proteínas/genética , Sulfurtransferases/genética , Atrofia , Criança , Pré-Escolar , Evolução Fatal , Feminino , Glutarredoxinas/química , Humanos , Hiperglicinemia não Cetótica/diagnóstico , Hiperglicinemia não Cetótica/patologia , Lactente , Masculino , Proteínas/química , Índice de Gravidade de Doença , Sulfurtransferases/química
15.
Mitochondrion ; 13(6): 656-61, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24063851

RESUMO

New mutations in mitochondrial DNA encoded genes of complex I are rarely reported. An infant developed Leigh disease with infantile spasms. Complex I enzyme activity was deficient and response to increasing coenzyme Q concentrations was reduced. Complex I assembly was intact. A new mutation in MT-ND1 m.3928G>C p.V208L, affecting a conserved amino acid in a critical domain, part of the coenzyme Q binding pocket, was present at high heteroplasmy. The unaffected mother did not carry measurable mutant mitochondrial DNA, but concern remained for gonadal mosaicism. Prenatal testing was possible for a subsequent sibling. The ND1 p.V208L mutation causes Leigh disease.


Assuntos
DNA Mitocondrial/genética , Doença de Leigh/genética , Mutação , Espasmo/etiologia , Feminino , Humanos , Lactente , Doença de Leigh/fisiopatologia , Imagem por Ressonância Magnética , Masculino , Linhagem
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