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1.
J Inherit Metab Dis ; 2020 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33141444

RESUMO

Adult polyglucosan body disease (APBD) represents a complex autosomal recessive inherited neurometabolic disorder due to homozygous or compound heterozygous pathogenic variants in GBE1 gene, resulting in deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies, involving the skeletal muscle, diaphragm, peripheral nerve (including autonomic fibers), brain white matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser extent heart, lung, kidney, and liver cells. The diversity of new clinical presentations regarding neuromuscular involvement is astonishing and transformed APBD in a key differential diagnosis of completely different clinical conditions, including axonal and demyelinating sensorimotor polyneuropathy, progressive spastic paraparesis, motor neuronopathy presentations, autonomic disturbances, leukodystrophies or even pure myopathic involvement with limb-girdle pattern of weakness. This review article aims to summarize the main clinical, biochemical, genetic, and diagnostic aspects regarding APBD with special focus on neuromuscular presentations.

2.
EMBO J ; 39(23): e105364, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33128823

RESUMO

Reversible infantile respiratory chain deficiency (RIRCD) is a rare mitochondrial myopathy leading to severe metabolic disturbances in infants, which recover spontaneously after 6-months of age. RIRCD is associated with the homoplasmic m.14674T>C mitochondrial DNA mutation; however, only ~ 1/100 carriers develop the disease. We studied 27 affected and 15 unaffected individuals from 19 families and found additional heterozygous mutations in nuclear genes interacting with mt-tRNAGlu including EARS2 and TRMU in the majority of affected individuals, but not in healthy carriers of m.14674T>C, supporting a digenic inheritance. Our transcriptomic and proteomic analysis of patient muscle suggests a stepwise mechanism where first, the integrated stress response associated with increased FGF21 and GDF15 expression enhances the metabolism modulated by serine biosynthesis, one carbon metabolism, TCA lipid oxidation and amino acid availability, while in the second step mTOR activation leads to increased mitochondrial biogenesis. Our data suggest that the spontaneous recovery in infants with digenic mutations may be modulated by the above described changes. Similar mechanisms may explain the variable penetrance and tissue specificity of other mtDNA mutations and highlight the potential role of amino acids in improving mitochondrial disease.

3.
J Transl Genet Genom ; 4: 81-90, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32601614

RESUMO

Aim: The North American Mitochondrial Disease Consortium (NAMDC) comprises a network of 17 clinical centers with a mission to conduct translational research on mitochondrial diseases. NAMDC is a part of the Rare Disease Clinical Research Network (RDCRN) and is funded by the National Institutes of Health. To foster its mission, NAMDC has implemented a comprehensive Mitochondrial Disease Clinical Registry (hereafter NAMDC Registry), collected biosamples deposited into the NAMDC Biorepository, defined phenotypes and genotypes of specific disorders, collected natural history data, identified outcome measures, characterized safety and long-term toxicity and efficacy of promising therapies, and trained young investigators interested in patient-oriented research in mitochondrial disease. Methods: Research conducted by NAMDC is built on the foundation of the Clinical Registry. Data within the registry are encrypted and maintained in a centralized database at Columbia University Medical Center. In addition to clinical data, NAMDC has established a mitochondrial disease biorepository, collecting DNA, plasma, cell, and tissue samples. Specimens are assigned coded identifiers in compliance with all relevant regulatory entities and with emerging NIH guidelines for biorepositories. NAMDC funds two pilot projects each year. Pilot grants are small grants typically supporting an early stage concept to obtain preliminary data. Pilot grants must enhance and address major issues in mitochondrial medicine and specific areas of need for the field and for the successful outcome of NAMDC. The grant selection process is facilitated by input from multiple stakeholders including patient organizations and the strategic leadership of NAMDC. To train new mitochondrial disease investigators, NAMDC has established a Fellowship Program which offers a unique training opportunity to senior postdoctoral clinical fellows. The fellowship includes a 6-month period of intensive training in clinical trial methodology through the Clinical Research Enhancement through Supplemental Training program and equivalent programs at the other sites, along with rotations up to 3 months each to two additional consortium sites where a rich and varied training experience is provided. Nine core educational sites participate in this training program, each offering a summer grant program in mitochondrial medicine funded by our NAMDC partner the United Mitochondrial Disease Foundation (www.umdf.org). All clinical research in NAMDC depends on the participation of mitochondrial disease patients. Since individual mitochondrial disorders are often extremely rare, major communication and recruitment efforts are required. Therefore, NAMDC has forged a very close partnership with the premier patient advocacy group for mitochondrial diseases in North America, the United Mitochondrial Disease Foundation (UMDF). Results: The NAMDC Registry has confirmed the clinical and genetical heterogeneity of mitochondrial diseases due to primary mutations in mitochondrial DNA or nuclear DNA. During the 8 years of this NIH-U54 grant, this consortium, acting in close collaboration with a patient advocacy group, the UMDF, has effectively addressed these complex diseases. NAMDC has expanded a powerful patient registry with more than 1600 patients enrolled to date, a website for education and recruitment of patients (www.namdc.org), a NAMDC biorepository housed at the Mayo Clinic in Rochester, MN, and essential diagnostic guidelines for consensus research. In addition, eight clinical studies have been initiated and the NAMDC fellowship program has been actively training the next generation of mitochondrial disease clinical investigators, of which six have completed the program and remain actively involved in mitochondrial disease research. Conclusion: The NAMDC Patient Registry and Biorepository is actively facilitating mitochondrial disease research, and accelerating progress in the understanding and treatment of mitochondrial diseases.

4.
Neurol Genet ; 6(2): e402, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32337332

RESUMO

Objective: To describe clinical, biochemical, and genetic features of participants with mitochondrial diseases (MtDs) enrolled in the North American Mitochondrial Disease Consortium (NAMDC) Registry. Methods: This cross-sectional, multicenter, retrospective database analysis evaluates the phenotypic and molecular characteristics of participants enrolled in the NAMDC Registry from September 2011 to December 2018. The NAMDC is a network of 17 centers with expertise in MtDs and includes both adult and pediatric specialists. Results: One thousand four hundred ten of 1,553 participants had sufficient clinical data for analysis. For this study, we included only participants with molecular genetic diagnoses (n = 666). Age at onset ranged from infancy to adulthood. The most common diagnosis was multisystemic disorder (113 participants), and only a minority of participants were diagnosed with a classical mitochondrial syndrome. The most frequent classical syndromes were Leigh syndrome (97 individuals) and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (71 individuals). Pathogenic variants in the mitochondrial DNA were more frequently observed (414 participants) than pathogenic nuclear gene variants (252 participants). Pathogenic variants in 65 nuclear genes were identified, with POLG1 and PDHA1 being the most commonly affected. Pathogenic variants in 38 genes were reported only in single participants. Conclusions: The NAMDC Registry data confirm the high variability of clinical, biochemical, and genetic features of participants with MtDs. This study serves as an important resource for future enhancement of MtD research and clinical care by providing the first comprehensive description of participant with MtD in North America.

5.
Int J Mol Sci ; 20(22)2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31718067

RESUMO

The history of "mitochondrial pathologies", namely genetic pathologies affecting mitochondrial metabolism because of mutations in nuclear DNA-encoded genes for proteins active inside mitochondria or mutations in mitochondrial DNA-encoded genes, began in 1988. In that year, two different groups of researchers discovered, respectively, large-scale single deletions of mitochondrial DNA (mtDNA) in muscle biopsies from patients with "mitochondrial myopathies" and a point mutation in the mtDNA gene for subunit 4 of NADH dehydrogenase (MTND4), associated with maternally inherited Leber's hereditary optic neuropathy (LHON). Henceforth, a novel conceptual "mitochondrial genetics", separate from mendelian genetics, arose, based on three features of mtDNA: (1) polyplasmy; (2) maternal inheritance; and (3) mitotic segregation. Diagnosis of mtDNA-related diseases became possible through genetic analysis and experimental approaches involving histochemical staining of muscle or brain sections, single-fiber polymerase chain reaction (PCR) of mtDNA, and the creation of patient-derived "cybrid" (cytoplasmic hybrid) immortal fibroblast cell lines. The availability of the above-mentioned techniques along with the novel sensitivity of clinicians to such disorders led to the characterization of a constantly growing number of pathologies. Here is traced a brief historical perspective on the discovery of autonomous pathogenic mtDNA mutations and on the related mendelian pathology altering mtDNA integrity.


Assuntos
DNA Mitocondrial/genética , Mitocôndrias/patologia , Doenças Mitocondriais/história , Doenças Mitocondriais/patologia , Proteínas Mitocondriais/metabolismo , Mutação , História do Século XX , História do Século XXI , Humanos , Mitocôndrias/metabolismo , Doenças Mitocondriais/genética , Proteínas Mitocondriais/genética
6.
Mitochondrion ; 49: 25-34, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31271879

RESUMO

Leigh syndrome represents a complex inherited neurometabolic and neurodegenerative disorder associated with different clinical, genetic and neuroimaging findings in the context of bilateral symmetrical lesions involving the brainstem and basal ganglia. Heterogeneous neurological manifestations such as spasticity, cerebellar ataxia, dystonia, choreoathetosis and parkinsonism are associated with multisystemic and ophthalmological abnormalities due to >75 different monogenic causes. Here, we describe the clinical and genetic features of a Brazilian cohort of patients with Leigh Syndrome in which muscle biopsy analysis showed mitochondrial DNA defects and determine the utility of whole exome sequencing for a final genetic diagnostic in this cohort.


Assuntos
DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Doença de Leigh/genética , Doença de Leigh/metabolismo , Sequenciamento Completo do Exoma , Adolescente , Adulto , Idoso , Brasil , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Doença de Leigh/diagnóstico , Masculino , Pessoa de Meia-Idade
7.
J Mol Med (Berl) ; 97(9): 1231-1243, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31053970

RESUMO

During infection, hepatocytes must undergo a reprioritization of metabolism, termed metabolic reprogramming. Hepatic metabolic reprogramming in response to infection begins within hours of infection, suggesting a mechanism closely linked to pathogen recognition. Following injection with polyinosinic:polycytidylic acid, a mimic of viral infection, a robust hepatic innate immune response could be seen involving the TNFα pathway at 2 h. Repeated doses led to the adoption of Warburg-like metabolism in the liver as determined by in vivo metabolic imaging, expression analyses, and metabolomics. Hepatic macrophages, Kupffer cells, were able to induce Warburg-like metabolism in hepatocytes in vitro via TNFα. Eliminating macrophages in vivo or blocking TNFα in vitro or in vivo resulted in abrogation of the metabolic phenotype, establishing an immune-metabolic axis in hepatic metabolic reprogramming. Overall, we suggest that macrophages, as early sensors of pathogens, instruct hepatocytes via TNFα to undergo metabolic reprogramming to cope with challenges to homeostasis initiated by infection. This work not only addresses a key component of end-organ physiology, but also raises questions about the side effects of biologics in the treatment of inflammatory diseases. KEY MESSAGES: • Hepatocytes develop Warburg-like metabolism in vivo during viral infection. • Macrophage TNFα promotes expression of glycolytic enzymes in hepatocytes. • Blocking this immune-metabolic axis abrogates Warburg-like metabolism in the liver. • Implications for patients being treated for inflammatory diseases with biologics.


Assuntos
Hepatócitos/metabolismo , Fígado/metabolismo , Macrófagos/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Produtos Biológicos/farmacologia , Linhagem Celular Tumoral , Hepatócitos/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Homeostase/fisiologia , Humanos , Imunidade Inata/efeitos dos fármacos , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Fígado/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL
8.
Curr Neuropharmacol ; 17(1): 21-32, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29119930

RESUMO

BACKGROUND: Hereditary cerebellar ataxias are a group of disorders characterized by heterogeneous clinical manifestations, progressive clinical course, and diverse genetic causes. No disease modifying treatments are yet available for many of these disorders. Oxidative stress has been recurrently identified in different progressive cerebellar diseases, and it represents a widely investigated target for treatment. OBJECTIVE: To review the main aspects and new perspectives of antioxidant therapy in cerebellar ataxias ranging from bench to bedside. METHOD: This article is a summary of the state-of-the-art on the use of antioxidant molecules in cerebellar ataxia treatments. It also briefly summarizes aspects of oxidative stress production and general characteristics of antioxidant compounds. RESULTS: Antioxidants represent a vast category of compounds; old drugs have been extensively studied and modified in order to achieve better biological effects. Despite the vast body of literature present on the use of antioxidants in cerebellar ataxias, for the majority of these disorders conclusive results on the efficacy are still missing. CONCLUSION: Antioxidant therapy in cerebellar ataxias is a promising field of investigations. To achieve the success in identifying the correct treatment more work needs to be done. In particular, a combined effort is needed by basic scientists in developing more efficient molecules, and by clinical researchers together with patients communities, to run clinical trials in order to identify conclusive treatments strategies.


Assuntos
Antioxidantes/uso terapêutico , Ataxia Cerebelar/tratamento farmacológico , Animais , Ataxia Cerebelar/metabolismo , Humanos , Estresse Oxidativo/efeitos dos fármacos
9.
JCI Insight ; 3(23)2018 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-30518688

RESUMO

Methylmalonic acidemia (MMA), an organic acidemia characterized by metabolic instability and multiorgan complications, is most frequently caused by mutations in methylmalonyl-CoA mutase (MUT). To define the metabolic adaptations in MMA in acute and chronic settings, we studied a mouse model generated by transgenic expression of Mut in the muscle. Mut-/-;TgINS-MCK-Mut mice accurately replicate the hepatorenal mitochondriopathy and growth failure seen in severely affected patients and were used to characterize the response to fasting. The hepatic transcriptome in MMA mice was characterized by the chronic activation of stress-related pathways and an aberrant fasting response when compared with controls. A key metabolic regulator, Fgf21, emerged as a significantly dysregulated transcript in mice and was subsequently studied in a large patient cohort. The concentration of plasma FGF21 in MMA patients correlated with disease subtype, growth indices, and markers of mitochondrial dysfunction but was not affected by renal disease. Restoration of liver Mut activity, by transgenesis and liver-directed gene therapy in mice or liver transplantation in patients, drastically reduced plasma FGF21 and was associated with improved outcomes. Our studies identify mitocellular hormesis as a hepatic adaptation to metabolic stress in MMA and define FGF21 as a highly predictive disease biomarker.


Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Hormese , Metilmalonil-CoA Mutase/metabolismo , Estresse Fisiológico , Erros Inatos do Metabolismo dos Aminoácidos/genética , Erros Inatos do Metabolismo dos Aminoácidos/patologia , Animais , Biomarcadores/sangue , Modelos Animais de Doenças , Feminino , Fatores de Crescimento de Fibroblastos/sangue , Terapia Genética , Humanos , Nefropatias/metabolismo , Fígado/metabolismo , Fígado/patologia , Transplante de Fígado , Masculino , Metilmalonil-CoA Mutase/genética , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Fenótipo , Transcriptoma
10.
Neurology ; 91(11): e1077-e1082, 2018 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-30111548

RESUMO

OBJECTIVE: To study the variable clinical picture and exercise tolerance of patients with phosphoglycerate kinase (PGK) 1 deficiency and how it relates to residual PGK enzyme activity. METHODS: In this case series study, we evaluated 7 boys and men from 5 families with PGK1 deficiency. Five had pure muscle symptoms, while 2 also had mild intellectual disability with or without anemia. Muscle glycolytic and oxidative capacities were evaluated by an ischemic forearm exercise test and by cycle ergometry. RESULTS: Enzyme levels of PGK were 4% to 9% of normal in red cells and 5% to10% in muscle in pure myopathy patients and 2.6% in both muscle and red cells in the 2 patients with multisystem involvement. Patients with pure myopathy had greater increases in lactate with ischemic exercise (2-3 mmol/L) vs the 2 multisystem-affected patients (<1 mmol/L). Myopathy patients had higher oxidative capacity in cycle exercise vs multisystem affected patients (≈30 vs ≈15 mL/kg per minute). One multisystem-affected patient developed frank myoglobinuria after the short exercise test. CONCLUSIONS: This case series study of PGK1 deficiency suggests that the level of impaired glycolysis in PGK deficiency is a major determinant of phenotype. Lower glycolytic capacity in PGK1 deficiency seems to result in multisystem involvement and increased susceptibility to exertional rhabdomyolysis.


Assuntos
Tolerância ao Exercício/fisiologia , Doenças Genéticas Ligadas ao Cromossomo X/enzimologia , Doenças Genéticas Ligadas ao Cromossomo X/fisiopatologia , Erros Inatos do Metabolismo/enzimologia , Erros Inatos do Metabolismo/fisiopatologia , Fosfoglicerato Quinase/deficiência , Fosfoglicerato Quinase/metabolismo , Ergometria , Teste de Esforço , Doenças Genéticas Ligadas ao Cromossomo X/complicações , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico , Humanos , Deficiência Intelectual/sangue , Deficiência Intelectual/complicações , Deficiência Intelectual/enzimologia , Deficiência Intelectual/fisiopatologia , Ácido Láctico/sangue , Masculino , Erros Inatos do Metabolismo/complicações , Erros Inatos do Metabolismo/diagnóstico , Músculo Esquelético/metabolismo , Doenças Musculares/sangue , Doenças Musculares/complicações , Doenças Musculares/enzimologia , Doenças Musculares/fisiopatologia , Fenótipo , Fosfoglicerato Quinase/sangue
11.
J Med Genet ; 55(8): 515-521, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29602790

RESUMO

BACKGROUND: Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessive TK2 mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy. OBJECTIVE: To perform a retrospective natural history study of a large cohort of patients with TK2 deficiency. METHODS: The study was conducted by 42 investigators across 31 academic medical centres. RESULTS: We identified 92 patients with genetically confirmed diagnoses of TK2 deficiency: 67 from literature review and 25 unreported cases. Based on clinical and molecular genetics findings, we recognised three phenotypes with divergent survival: (1) infantile-onset myopathy (42.4%) with severe mitochondrial DNA (mtDNA) depletion, frequent neurological involvement and rapid progression to early mortality (median post-onset survival (POS) 1.00, CI 0.58 to 2.33 years); (2) childhood-onset myopathy (40.2%) with mtDNA depletion, moderate-to-severe progression of generalised weakness and median POS at least 13 years; and (3) late-onset myopathy (17.4%) with mild limb weakness at onset and slow progression to respiratory insufficiency with median POS of 23 years. Ophthalmoparesis and facial weakness are frequent in adults. Muscle biopsies show multiple mtDNA deletions often with mtDNA depletion. CONCLUSIONS: In TK2 deficiency, age at onset, rate of weakness progression and POS are important variables that define three clinical subtypes. Nervous system involvement often complicates the clinical course of the infantile-onset form while extraocular muscle and facial involvement are characteristic of the late-onset form. Our observations provide essential information for planning future clinical trials in this disorder.


Assuntos
Estudos de Associação Genética , Predisposição Genética para Doença , Proteínas Mitocondriais/deficiência , Doenças Musculares/diagnóstico , Doenças Musculares/genética , Timidina Quinase/deficiência , Adolescente , Adulto , Idade de Início , Idoso , Criança , Pré-Escolar , Feminino , Genes Recessivos , Testes Genéticos , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiopatologia , Doenças Musculares/mortalidade , Mutação , Fenótipo , Estudos Retrospectivos , Análise de Sobrevida , Adulto Jovem
12.
Hum Mol Genet ; 26(21): 4257-4266, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28973171

RESUMO

Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encephalomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243 A > G mutation was excluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567 G > A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a human disease and encodes an enzyme responsible for 2'-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2'-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead completely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243 A > G negative MELAS-like presentation.


Assuntos
Síndrome MELAS/genética , Metiltransferases/genética , Metiltransferases/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Sequência de Aminoácidos , Criança , DNA Mitocondrial/genética , Humanos , Síndrome MELAS/diagnóstico , Masculino , Mitocôndrias/genética , Encefalomiopatias Mitocondriais/genética , Encefalomiopatias Mitocondriais/metabolismo , Mutação , RNA Ribossômico/genética , RNA Ribossômico/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Saccharomyces cerevisiae/genética
13.
Am J Hum Genet ; 101(4): 525-538, 2017 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-28942965

RESUMO

Complement component 1 Q subcomponent-binding protein (C1QBP; also known as p32) is a multi-compartmental protein whose precise function remains unknown. It is an evolutionary conserved multifunctional protein localized primarily in the mitochondrial matrix and has roles in inflammation and infection processes, mitochondrial ribosome biogenesis, and regulation of apoptosis and nuclear transcription. It has an N-terminal mitochondrial targeting peptide that is proteolytically processed after import into the mitochondrial matrix, where it forms a homotrimeric complex organized in a doughnut-shaped structure. Although C1QBP has been reported to exert pleiotropic effects on many cellular processes, we report here four individuals from unrelated families where biallelic mutations in C1QBP cause a defect in mitochondrial energy metabolism. Infants presented with cardiomyopathy accompanied by multisystemic involvement (liver, kidney, and brain), and children and adults presented with myopathy and progressive external ophthalmoplegia. Multiple mitochondrial respiratory-chain defects, associated with the accumulation of multiple deletions of mitochondrial DNA in the later-onset myopathic cases, were identified in all affected individuals. Steady-state C1QBP levels were decreased in all individuals' samples, leading to combined respiratory-chain enzyme deficiency of complexes I, III, and IV. C1qbp-/- mouse embryonic fibroblasts (MEFs) resembled the human disease phenotype by showing multiple defects in oxidative phosphorylation (OXPHOS). Complementation with wild-type, but not mutagenized, C1qbp restored OXPHOS protein levels and mitochondrial enzyme activities in C1qbp-/- MEFs. C1QBP deficiency represents an important mitochondrial disorder associated with a clinical spectrum ranging from infantile lactic acidosis to childhood (cardio)myopathy and late-onset progressive external ophthalmoplegia.


Assuntos
Cardiomiopatias/genética , Proteínas de Transporte/genética , Transporte de Elétrons/fisiologia , Doenças Mitocondriais/genética , Proteínas Mitocondriais/genética , Mutação , Adulto , Idade de Início , Idoso , Alelos , Sequência de Aminoácidos , Animais , Cardiomiopatias/complicações , Cardiomiopatias/patologia , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Células Cultivadas , Pré-Escolar , Estudos de Coortes , DNA Mitocondrial , Embrião de Mamíferos/metabolismo , Embrião de Mamíferos/patologia , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Humanos , Recém-Nascido , Masculino , Camundongos , Pessoa de Meia-Idade , Doenças Mitocondriais/complicações , Doenças Mitocondriais/patologia , Proteínas Mitocondriais/química , Proteínas Mitocondriais/metabolismo , Fosforilação Oxidativa , Linhagem , Conformação Proteica , Homologia de Sequência , Índice de Gravidade de Doença , Adulto Jovem
14.
Cell Metab ; 25(6): 1254-1268.e7, 2017 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-28591633

RESUMO

T cells undergo metabolic reprogramming with major changes in cellular energy metabolism during activation. In patients with mitochondrial disease, clinical data were marked by frequent infections and immunodeficiency, prompting us to explore the consequences of oxidative phosphorylation dysfunction in T cells. Since cytochrome c oxidase (COX) is a critical regulator of OXPHOS, we created a mouse model with isolated dysfunction in T cells by targeting a gene, COX10, that produces mitochondrial disease in humans. COX dysfunction resulted in increased apoptosis following activation in vitro and immunodeficiency in vivo. Select T cell effector subsets were particularly affected; this could be traced to their bioenergetic requirements. In summary, the findings presented herein emphasize the role of COX particularly in T cells as a metabolic checkpoint for cell fate decisions following T cell activation, with heterogeneous effects in T cell subsets. In addition, our studies highlight the utility of translational models that recapitulate human mitochondrial disease for understanding immunometabolism.


Assuntos
Alquil e Aril Transferases/imunologia , Diferenciação Celular/imunologia , Complexo IV da Cadeia de Transporte de Elétrons/imunologia , Ativação Linfocitária , Proteínas de Membrana/imunologia , Doenças Mitocondriais/imunologia , Linfócitos T/imunologia , Alquil e Aril Transferases/genética , Animais , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Humanos , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Doenças Mitocondriais/genética
15.
Nat Rev Dis Primers ; 2: 16080, 2016 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-27775730

RESUMO

Mitochondrial diseases are a group of genetic disorders that are characterized by defects in oxidative phosphorylation and caused by mutations in genes in the nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) that encode structural mitochondrial proteins or proteins involved in mitochondrial function. Mitochondrial diseases are the most common group of inherited metabolic disorders and are among the most common forms of inherited neurological disorders. One of the challenges of mitochondrial diseases is the marked clinical variation seen in patients, which can delay diagnosis. However, advances in next-generation sequencing techniques have substantially improved diagnosis, particularly in children. Establishing a genetic diagnosis allows patients with mitochondrial diseases to have reproductive options, but this is more challenging for women with pathogenetic mtDNA mutations that are strictly maternally inherited. Recent advances in in vitro fertilization techniques, including mitochondrial donation, will offer a better reproductive choice for these women in the future. The treatment of patients with mitochondrial diseases remains a challenge, but guidelines are available to manage the complications of disease. Moreover, an increasing number of therapeutic options are being considered, and with the development of large cohorts of patients and biomarkers, several clinical trials are in progress.


Assuntos
Doenças Mitocondriais/diagnóstico , Doenças Mitocondriais/fisiopatologia , Doenças Mitocondriais/terapia , Terapia Genética/métodos , Humanos , Mitocôndrias/genética , Mitocôndrias/patologia , Fosforilação Oxidativa
16.
Eur J Med Genet ; 59(10): 540-5, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27592148

RESUMO

Mitochondrial DNA (mtDNA) depletion syndrome manifests as diverse early-onset diseases that affect skeletal muscle, brain and liver function. Mutations in several nuclear DNA-encoded genes cause mtDNA depletion. We report on a patient, a 3-month-old boy who presented with hepatic failure, and was found to have severe mtDNA depletion in liver and muscle. Whole-exome sequencing identified a homozygous missense variant (c.544C > T, p.R182W) in the accessory subunit of mitochondrial DNA polymerase gamma (POLG2), which is required for mitochondrial DNA replication. This variant is predicted to disrupt a critical region needed for homodimerization of the POLG2 protein and cause loss of processive DNA synthesis. Both parents were phenotypically normal and heterozygous for this variant. Heterozygous mutations in POLG2 were previously associated with progressive external ophthalmoplegia and mtDNA deletions. This is the first report of a patient with a homozygous mutation in POLG2 and with a clinical presentation of severe hepatic failure and mitochondrial depletion.


Assuntos
DNA Mitocondrial/genética , DNA Polimerase Dirigida por DNA/genética , Pseudo-Obstrução Intestinal/genética , Falência Hepática Aguda/genética , Encefalomiopatias Mitocondriais/genética , Sequência de Bases , Exoma/genética , Humanos , Lactente , Pseudo-Obstrução Intestinal/complicações , Pseudo-Obstrução Intestinal/fisiopatologia , Falência Hepática Aguda/complicações , Falência Hepática Aguda/fisiopatologia , Masculino , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Encefalomiopatias Mitocondriais/complicações , Encefalomiopatias Mitocondriais/fisiopatologia , Distrofia Muscular Oculofaríngea , Mutação de Sentido Incorreto , Oftalmoplegia/congênito
17.
Mol Genet Metab ; 118(1): 28-34, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26992325

RESUMO

Defects in the tricarboxylic acid cycle (TCA) are associated with a spectrum of neurological phenotypes that are often difficult to diagnose and manage. Whole-exome sequencing (WES) led to a rapid expansion of diagnostic capabilities in such disorders and facilitated a better understanding of disease pathogenesis, although functional characterization remains a bottleneck to the interpretation of potential pathological variants. We report a 2-year-old boy of Afro-Caribbean ancestry, who presented with neuromuscular symptoms without significant abnormalities on routine diagnostic evaluation. WES revealed compound heterozygous missense variants of uncertain significance in mitochondrial aconitase (ACO2), which encodes the TCA enzyme ACO2. Pathogenic variants in ACO2 have been described in a handful of families as the cause of infantile cerebellar-retinal degeneration syndrome. Using biochemical and cellular assays in patient fibroblasts, we found that ACO2 expression was quantitatively normal, but ACO2 enzyme activity was <20% of that observed in control cells. We also observed a deficiency in cellular respiration and, for the first time, demonstrate evidence of mitochondrial DNA depletion and altered expression of some TCA components and electron transport chain subunits. The observed cellular defects were completely restored with ACO2 gene rescue. Our findings demonstrate the pathogenicity of two VUS in ACO2, provide novel mechanistic insights to TCA disturbances in ACO2 deficiency, and implicate mitochondrial DNA depletion in the pathogenesis of this recently described disorder.


Assuntos
Aconitato Hidratase/deficiência , Aconitato Hidratase/genética , Erros Inatos do Metabolismo/genética , Mutação de Sentido Incorreto , Doenças Neuromusculares/genética , Pré-Escolar , Ciclo do Ácido Cítrico , DNA Mitocondrial/genética , Exoma , Regulação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Masculino , Erros Inatos do Metabolismo/etnologia , Erros Inatos do Metabolismo/metabolismo , Doenças Neuromusculares/etnologia , Doenças Neuromusculares/metabolismo
18.
Hum Reprod ; 31(5): 1058-65, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26936885

RESUMO

STUDY QUESTION: Among women who carry pathogenic mitochondrial DNA (mtDNA) point mutations and healthy oocyte donors, what are the levels of support for developing oocyte mitochondrial replacement therapy (OMRT) to prevent transmission of mtDNA mutations? SUMMARY ANSWER: The majority of mtDNA carriers and oocyte donors support the development of OMRT techniques to prevent transmission of mtDNA diseases. WHAT IS KNOWN ALREADY: Point mutations of mtDNA cause a variety of maternally inherited human diseases that are frequently disabling and often fatal. Recent developments in (OMRT) as well as pronuclear transfer between embryos offer new potential options to prevent transmission of mtDNA disease. However, it is unclear whether the non-scientific community will approve of embryos that contain DNA from three people. STUDY DESIGN, SIZE, DURATION: Between 1 June 2012 through 12 February 2015, we administered surveys in cross-sectional studies of 92 female carriers of mtDNA point mutations and 112 healthy oocyte donors. PARTICIPANTS/MATERIALS, SETTING, METHODS: The OMRT carrier survey was completed by 92 female carriers of an mtDNA point mutation. Carriers were recruited through the North American Mitochondrial Disease Consortium (NAMDC), the United Mitochondrial Disease Foundation (UMDF), patient support groups, research and private patients followed at the Columbia University Medical Center (CUMC) and patients' referrals of maternal relatives. The OMRT donor survey was completed by 112 women who had donated oocytes through a major ITALIC! in vitro fertilization clinic. MAIN RESULTS AND THE ROLE OF CHANCE: All carriers surveyed were aware that they could transmit the mutation to their offspring, with 78% (35/45) of women, who were of childbearing age, indicating that the risk was sufficient to consider not having children, and 95% (87/92) of all carriers designating that the development of this technique was important and worthwhile. Of the 21 surveyed female carriers considering childbearing, 20 (95%) considered having their own biological offspring somewhat or very important and 16 of the 21 respondents (76%) were willing to donate oocytes for research and development. Of 112 healthy oocyte donors who completed the OMRT donor survey, 97 (87%) indicated that they would donate oocytes for generating a viable embryo through OMRT. LIMITATIONS, REASONS FOR CAUTION: Many of the participants were either patients or relatives of patients who were already enrolled in a research-oriented database, or who sought care in a tertiary research university setting, indicating a potential sampling bias. The survey was administered to a select group of individuals, who carry, or are at risk for carrying, mtDNA point mutations. These individuals are more likely to have been affected by the mutation or have witnessed first-hand the devastating effects of these mutations. It has not been established whether the general public would be supportive of this work. This survey did not explicitly address alternatives to OMRT. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study indicating a high level of interest in the development of these methods among women affected by the diseases or who are at risk of carrying mtDNA mutations as well as willingness of most donors to provide oocytes for the development of OMRT. STUDY FUNDING/COMPETING INTERESTS: This work was conducted under the auspices of the NAMDC (Study Protocol 7404). NAMDC (U54NS078059) is part of the NCATS Rare Diseases Clinical Research Network (RDCRN). RDCRN is an initiative of the Office of Rare Diseases Research (ORDR) and NCATS. NAMDC is funded through a collaboration between NCATS, NINDS, NICHD and NIH Office of Dietary Supplements. The work was also supported by the Bernard and Anne Spitzer Fund and the New York Stem Cell Foundation (NYSCF). Dr Hirano has received research support from Santhera Pharmaceuticals and Edison Pharmaceuticals for studies unrelated to this work. None of the other authors have conflicts of interest. TRIAL REGISTRATION NUMBER: Not applicable.


Assuntos
Atitude , Heterozigoto , Doenças Mitocondriais/prevenção & controle , Terapia de Substituição Mitocondrial/psicologia , Adulto , Estudos Transversais , DNA Mitocondrial/química , Feminino , Humanos , Doenças Mitocondriais/genética , Doenças Mitocondriais/psicologia , Mutação Puntual
19.
Child Neurol Open ; 3: 2329048X15627937, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28503604

RESUMO

Dystonia is often associated with the symmetrical basal ganglia lesions of Leigh syndrome. However, it has also been associated with mitochondrial ND mutations, with or without Leber hereditary optic neuropathy. The m.14459G>A mutation in ND6 causes dystonia with or without familial Leber hereditary optic neuropathy. We report heteroplasmic 14459G>A mutations in 2 unrelated children with nonmaternally inherited generalized dystonia and showing bilateral magnetic resonance imaging lesions in nucleus pallidus and putamen. Both children have reached their teenage years, and they are intellectually active, despite their motor problems.

20.
Neuromuscul Disord ; 26(1): 16-20, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26652229

RESUMO

Five Sardinian patients presented in their 5th or 6th decade with progressive limb girdle muscle weakness but their muscle biopsies showed vacuolar myopathy. The more or less abundant subsarcolemmal and intermyofibrillar vacuoles showed intense, partially α-amylase resistant, PAS-positive deposits consistent with polyglucosan. The recent description of late-onset polyglucosan myopathy has prompted us to find new genetic defects in the gene (GYG1) encoding glycogenin-1, the crucial primer enzyme of glycogen synthesis in muscle. We found a single homozygous intronic mutation harbored by five patients, who, except for two siblings, appear to be unrelated but all five live in central or south Sardinian villages.


Assuntos
Glucanos/genética , Glucosiltransferases/genética , Doença de Depósito de Glicogênio/genética , Glicoproteínas/genética , Mutação/genética , Doenças do Sistema Nervoso/genética , Adulto , Idoso , Análise Mutacional de DNA , Feminino , Homozigoto , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/patologia , Músculo Esquelético/ultraestrutura
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