RESUMO
Mutations in KARS, which encodes for both mitochondrial and cytoplasmic lysyl-tRNA synthetase, have been so far associated with three different phenotypes: the recessive form of Charcot-Mary-Tooth polyneuropathy, the autosomal recessive nonsyndromic hearing loss and the last recently described condition related to congenital visual impairment and progressive microcephaly. Here we report the case of a 14-year-old girl with severe cardiomyopathy associated to mild psychomotor delay and mild myopathy; moreover, a diffuse reduction of cytochrome C oxidase (COX, complex IV) and a combined enzymatic defect of complex I (CI) and complex IV (CIV) was evident in muscle biopsy. Using the TruSight One sequencing panel we identified two novel mutations in KARS. Both mutations, never reported previously, occur in a highly conserved region of the catalytic domain and displayed a dramatic effect on KARS stability. Structural analysis confirmed the pathogenic role of the identified variants. Our findings confirm and emphasize that mt-aminoacyl-tRNA synthetases (mt-ARSs) enzymes are related to a broad clinical spectrum due to their multiple and still unknown functions.
Assuntos
Cardiomiopatia Hipertrófica/genética , Lisina-tRNA Ligase/genética , Doenças Mitocondriais/genética , Transtornos Psicomotores/genética , Adolescente , Cardiomiopatia Hipertrófica/complicações , Cardiomiopatia Hipertrófica/patologia , Transporte de Elétrons/genética , Feminino , Predisposição Genética para Doença , Humanos , Mitocôndrias/genética , Mitocôndrias/patologia , Doenças Mitocondriais/complicações , Doenças Mitocondriais/patologia , Mutação , Fenótipo , Transtornos Psicomotores/complicações , Transtornos Psicomotores/patologiaRESUMO
DJ-1 mutations are associated to early-onset Parkinson's disease and accounts for about 1-2% of the genetic forms. The protein is involved in many biological processes and its role in mitochondrial regulation is gaining great interest, even if its function in mitochondria is still unclear. We describe a 47-year-old woman affected by a multisystem disorder characterized by progressive, early-onset parkinsonism plus distal spinal amyotrophy, cataracts and sensory-neural deafness associated with a novel homozygous c.461C>A [p.T154K] mutation in DJ-1. Patient's cultured fibroblasts showed low ATP synthesis, high ROS levels and reduced amount of some subunits of mitochondrial complex I; biomarkers of oxidative stress also resulted abnormal in patient's blood. The clinical pattern of multisystem involvement and the biochemical findings in our patient highlight the role for DJ-1 in modulating mitochondrial response against oxidative stress.
Assuntos
Fibroblastos/metabolismo , Estresse Oxidativo/genética , Doença de Parkinson/genética , Proteína Desglicase DJ-1/genética , Trifosfato de Adenosina/biossíntese , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Feminino , Fibroblastos/patologia , Homozigoto , Humanos , Pessoa de Meia-Idade , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mutação , Doença de Parkinson/patologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
NDUFB11, a component of mitochondrial complex I, is a relatively small integral membrane protein, belonging to the "supernumerary" group of subunits, but proved to be absolutely essential for the assembly of an active complex I. Mutations in the X-linked nuclear-encoded NDUFB11 gene have recently been discovered in association with two distinct phenotypes, i.e. microphthalmia with linear skin defects and histiocytoid cardiomyopathy. We report on a male with complex I deficiency, caused by a de novo mutation in NDUFB11 and displaying early-onset sideroblastic anemia as the unique feature. This is the third report that describes a mutation in NDUFB11, but all are associated with a different phenotype. Our results further expand the molecular spectrum and associated clinical phenotype of NDUFB11 defects.
Assuntos
Acidose Láctica/genética , Anemia Sideroblástica/genética , Complexo I de Transporte de Elétrons/genética , Microftalmia/genética , Acidose Láctica/complicações , Acidose Láctica/fisiopatologia , Anemia Sideroblástica/complicações , Anemia Sideroblástica/fisiopatologia , Criança , DNA Mitocondrial/genética , Complexo I de Transporte de Elétrons/deficiência , Predisposição Genética para Doença , Humanos , Masculino , Microftalmia/fisiopatologia , Mutação , Linhagem , Fenótipo , Tirosina-tRNA LigaseRESUMO
BACKGROUND: Mitochondrial DNA (mtDNA) mutations are important causes of human genetic disease, with mutations in tRNA genes particularly prevalent. In many patients, mutations are heteroplasmic, affecting a population of mtDNA molecules. Establishing the pathogenicity of homoplasmic mitochondrial tRNA (mt-tRNA) mutations, in which the mutation is present in every mtDNA molecule, is extremely difficult. These mutations must conform to specific pathogenic criteria, documenting unequivocally a functional defect of the mutant mt-tRNA. AIMS: To investigate the pathogenic nature of two homoplasmic mt-tRNA(Thr) deletions, m.15940delT (previously reported as pathogenic) and m.15937delA, by assessing the steady state levels of the mutant mt-tRNA in tissue and cell-line samples from six unrelated families, in which affected individuals were thoroughly investigated for mitochondrial DNA disease on the basis of clinical presentations. Rates of de novo mitochondrial protein synthesis were also examined in control and m.15937delA mutant fibroblasts. RESULTS: Our data strongly suggest that both single nucleotide deletions are neutral polymorphisms; no obvious defects were apparent in either steady state mt-tRNA(Thr) levels or rates of mitochondrial protein synthesis. CONCLUSIONS: These findings have important implications for the investigation of other families with suspected mtDNA disease, in particular the requirement to fulfil strict and established pathogenic criteria in order to avoid misattribution of pathogenicity to mt-tRNA variants.
Assuntos
DNA Mitocondrial/genética , Doenças Mitocondriais/diagnóstico , Doenças Mitocondriais/genética , Mutação , RNA de Transferência de Treonina/genética , RNA/genética , Adulto , Biópsia , Células Cultivadas , Criança , Análise Mutacional de DNA , Feminino , Fibroblastos , Humanos , Lactente , Masculino , Mitocôndrias Cardíacas/genética , Mitocôndrias Musculares/genética , Doenças Mitocondriais/fisiopatologia , Músculo Esquelético , Polimorfismo Genético , RNA Mitocondrial , Pele/citologiaRESUMO
Published mutations in deoxyguanosine kinase (DGUOK) cause mitochondrial DNA depletion and a clinical phenotype that consists of neonatal liver failure, nystagmus and hypotonia. In this series, we have identified 15 different mutations in the DGUOK gene from 9 kindreds. Among them, 12 have not previously been reported. Nonsense, splice site, or frame-shift mutations that produce truncated proteins predominate over missense mutations. All patients who harbor null mutations had early onset liver failure and significant neurological disease. These patients have all died before 2-years of age. Conversely, two patients carrying missense mutations had isolated liver disease and are alive in their 4th year of life without liver transplant. Five subjects were detected by newborn screening, with elevated tyrosine or phenylalanine. Consequently, this disease should be considered if elevated tyrosine is identified by newborn screening. Mitochondrial DNA content was below 10% of controls in liver in all but one case and modestly reduced in blood cells. With this paper a total of 39 different mutations in DGUOK have been identified. The most frequent mutation, c.763_c.766dupGATT, occurs in 8 unrelated kindreds. 70% of mutations occur in only one kindred, suggesting full sequencing of this gene is required for diagnosis. The presentation of one case with apparent viral hepatitis, without neurological disease, suggests that this disease should be considered in patients with infantile liver failure regardless of the presence of neurological features or apparent infectious etiology.
Assuntos
DNA Mitocondrial/genética , Mutação/genética , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Adolescente , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Especificidade de ÓrgãosRESUMO
Vici syndrome is a human inherited multi-system disorder caused by recessive mutations in EPG5, encoding the EPG5 protein that mediates the fusion of autophagosomes with lysosomes. Immunodeficiency characterized by lack of memory B cells and increased susceptibility to infection is an integral part of the condition, but the role of EPG5 in the immune system remains unknown. Here we show that EPG5 is indispensable for the transport of the TLR9 ligand CpG to the late endosomal-lysosomal compartment, and for TLR9-initiated signaling, a step essential for the survival of human memory B cells and their ultimate differentiation into plasma cells. Moreover, the predicted structure of EPG5 includes a membrane remodeling domain and a karyopherin-like domain, thus explaining its function as a carrier between separate vesicular compartments. Our findings indicate that EPG5, by controlling nucleic acids intracellular trafficking, links macroautophagy/autophagy to innate and adaptive immunity.
Assuntos
Imunidade Adaptativa , Autofagia/imunologia , DNA/metabolismo , Endossomos/metabolismo , Imunidade Inata , Lisossomos/metabolismo , Proteínas/metabolismo , RNA/metabolismo , Agenesia do Corpo Caloso/genética , Agenesia do Corpo Caloso/imunologia , Proteínas Relacionadas à Autofagia , Linfócitos B/imunologia , Transporte Biológico , Catarata/genética , Catarata/imunologia , Linhagem Celular , Humanos , Proteínas de Membrana Lisossomal , Mutação , Proteínas/genética , Receptor Toll-Like 9/metabolismo , Proteínas de Transporte VesicularRESUMO
Patients with McArdle's myopathy lack muscle glycogen phosphorylase (M-GP) activity. Regenerating and cultured muscle of patients with McArdle's myopathy presents a glycogen phosphorylase (GP) activity, but it is not firmly established whether M-GP or non-M-GP isoforms are expressed. We have cultured myoblasts from biopsy specimen of five patients with McArdle's myopathy. Skeletal muscle was cultured aneurally or was innervated by coculture with fetal rat spinal cord explants. In the patients' muscle biopsies and in their cultured innervated and aneural muscle we studied total GP activity, isoenzymatic pattern, reactivity with anti-M-GP antiserum, and presence of M-GP mRNA. There was no detectable enzymatic activity, no immunoreactivity with anti-M-GP antiserum, and no M-GP mRNA in the muscle biopsy of all patients. GP activity, M-GP isozyme, and anti-M-GP antiserum reactivity were present in patients' aneural cultures, increased after innervation, and were undistinguishable from control. M-GP mRNA was demonstrated in both aneural and innervated cultures of patients and control by primer extension and PCR amplification of total RNA. Our studies indicate that the M-GP gene is normally transcribed and translated in cultured muscle of patients with myophosphorylase deficiency.
Assuntos
Doença de Depósito de Glicogênio Tipo V/enzimologia , Doença de Depósito de Glicogênio Tipo V/genética , Isoenzimas/biossíntese , Músculos/enzimologia , Músculos/inervação , Fosforilases/biossíntese , Adulto , Sequência de Bases , Biópsia , Northern Blotting , Células Cultivadas , Criança , Primers do DNA , Eletroforese em Gel de Poliacrilamida , Feminino , Humanos , Isoenzimas/análise , Isoenzimas/genética , Cinética , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Músculos/patologia , Técnicas de Cultura de Órgãos , Fosforilases/deficiência , Fosforilases/isolamento & purificação , Reação em Cadeia da Polimerase , Medula Espinal/fisiologia , Medula Espinal/fisiopatologia , Fatores de TempoRESUMO
Mucopolysaccharidosis IVA is an autosomal recessive disease caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS). Mutation screening of the GALNS gene was performed for seven MPS IVA patients with attenuated phenotypes from three unrelated families. Four of 5 missense mutations identified in this study (p.F167V, p.R253W, p.R380S, p.P484S) and two reported (p.F97V, p.N204K), associated with attenuated phenotypes, were characterized using in vitro stable expression experiments, enzyme kinetic study, protein processing and structural analysis. The stably expressed mutant enzymes defining the attenuated phenotype exhibited a considerable residual activity (1.2-36.7% of the wild-type GALNS activity) except for p.R380S. Enzyme kinetic studies showed that p.F97V, p.F167V and p.N204K have lower affinity to the substrate compared with other mutants. The p.F97V enzyme was the most thermolabile at 55 degrees C. Immunoblot analyses indicated a rapid degradation and/or an insufficiency in processing in the mutant proteins. Tertiary structure analysis revealed that although there was a tendency for 'attenuated' mutant residues to be located on the surface of GALNS, they have a different effect on the protein including modification of the hydrophobic core and salt-bridge formation and different potential energy. This study demonstrates that 'attenuated' mutant enzymes are heterogeneous in molecular phenotypes, including biochemical properties and tertiary structure.
Assuntos
Condroitina Sulfatases/genética , Mucopolissacaridose IV/genética , Mutação de Sentido Incorreto , Adolescente , Adulto , Animais , Células CHO , Condroitina Sulfatases/química , Condroitina Sulfatases/deficiência , Condroitina Sulfatases/metabolismo , Cricetinae , Cricetulus , Análise Mutacional de DNA , Estabilidade Enzimática , Éxons , Feminino , Predisposição Genética para Doença , Temperatura Alta , Humanos , Interações Hidrofóbicas e Hidrofílicas , Itália , Japão , Cinética , Masculino , Pessoa de Meia-Idade , Modelos Moleculares , Mucopolissacaridose IV/enzimologia , Paquistão , Linhagem , Fenótipo , Processamento de Proteína Pós-Traducional , Estrutura Terciária de Proteína , Índice de Gravidade de Doença , Especificidade por Substrato , TransfecçãoRESUMO
BACKGROUND: Cytogenetic evidence suggests that the haploinsufficiency of > or =1 gene located in 8p23 behaves as a dominant mutation, impairing heart differentiation and leading to a wide spectrum of congenital heart defects (CHDs), including conotruncal lesions, atrial septal defects, atrioventricular canal defects, and pulmonary valve stenosis. An 8p heart-defect-critical region was delineated, and the zinc finger transcription factor GATA4 was considered a likely candidate for these defects. We narrowed this region and excluded a major role of GATA4 in these CHDs. METHODS AND RESULTS: We studied 12 patients (7 had CHD and 5 did not) with distal 8p deletions from 9 families by defining their chromosome rearrangements at the molecular level by fluorescent in situ hybridization and short-tandem repeat analysis. Subjects with 8p deletions distal to D8S1706, at approximately 10 cM from the 8p telomere, did not have CHD, whereas subjects with a deletion that included the more proximal region suffered from the spectrum of heart defects reported in patients with 8p distal deletions. The 5-cM critical region is flanked distally by D8S1706 and WI-8327, both at approximately 10 cM, and proximally by D8S1825, at 15 cM. Neither GATA4 nor angiopoietin-2 (ANGPT2; a gene in 8p23 involved in blood vessel formation) were found to be deleted in some of the critical patients. We also found that CHDs are not related to the parental origin of deletion. CONCLUSIONS: Haploinsufficiency for a gene between WI-8327 and D8S1825 is critical for heart development. A causal relationship does not seem to exist between GATA4 and ANGPT2 haploinsufficiency and CHDs.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 8 , Cardiopatias Congênitas/genética , Adolescente , Adulto , Criança , Pré-Escolar , Mapeamento Cromossômico , Feminino , Humanos , Recém-Nascido , Cariotipagem , MasculinoRESUMO
Sixteen unrelated Southern European patients with the mitochondrial depletion syndrome (MDS) were analyzed for mutations in the TK2 and DGUOK genes. Three novel mutations were identified in TK2 (R183G, R254X, and 142insG). When we analyzed additional genes involved in the dNTPs pool, such as SLC25A19 (DNC) and NT5M (d-NT2), we did not detect mutations. The current study suggest that scanning the TK2, DGUOK, SLC25A19, and NT5M genes is likely to help about 10% of MDS families in terms of genetic counseling. Also, our findings indicate that genotype-phenotype correlations are not straightforward in MDS.
Assuntos
DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Doenças Mitocondriais/genética , Idade de Início , Criança , Pré-Escolar , Análise Mutacional de DNA/métodos , Europa (Continente) , Feminino , Humanos , Lactente , Masculino , Mitocôndrias Musculares/enzimologia , Mitocôndrias Musculares/genética , Mitocôndrias Musculares/patologia , Doenças Mitocondriais/enzimologia , Doenças Mitocondriais/mortalidade , Doenças Mitocondriais/patologia , Mutação , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Estudos Retrospectivos , Síndrome , Timidina Quinase/genéticaRESUMO
X-linked Retinitis Pigmentosa (XLRP) shows a huge genetic heterogeneity with almost five distinct loci on the X chromosome. So far, only two XLRP genes have been identified, RPGR (or RP3) and RP2, being mutated in approximately 70% and 10% of the XLRP patients. Clinically there is no clearly significative difference between RP3 and RP2 phenotypes. In the attempt to assess the degree of involvement of the RP2 gene, we performed a complete mutation analysis in a cohort of patients and we identified five novel mutations in five different XLRP families. These mutations include three missense mutations, a splice site mutation, and a single base insertion, which, because of frameshift, anticipates a stop codon. Four mutations fall in RP2 exon 2 and one in exon 3. Evidence that such mutations are different from the 21 RP2 mutations described thus far suggests that a high mutation rate occurs at the RP2 locus, and that most mutations arise independently, without a founder effect. Our mutation analysis confirms the percentage of RP2 mutations detected so far in populations of different ethnic origin. In addition to novel mutations, we report here that a deeper sequence analysis of the RP2 product predicts, in addition to cofactor C homology domain, further putative functional domains, and that some novel mutations identify RP2 amino acid residues which are evolutionary conserved, hence possibly crucial to the RP2 function.
Assuntos
Ligação Genética/genética , Mutação/genética , Retinose Pigmentar/genética , Cromossomo X/genética , Sequência de Aminoácidos , Sequência de Bases , Estudos de Coortes , Sequência Conservada/genética , Análise Mutacional de DNA , Etnicidade/genética , Éxons/genética , Feminino , Heterogeneidade Genética , Humanos , Masculino , Dados de Sequência Molecular , Linhagem , Fenótipo , Polimorfismo Conformacional de Fita Simples , Estrutura Terciária de Proteína , Alinhamento de Sequência , Homologia de SequênciaRESUMO
Paralogous sequences on the same chromosome allow refolding of the chromosome into itself and homologous recombination. Recombinant chromosomes have microscopic or submicroscopic rearrangements according to the distance between repeats. Examples are the submicroscopic inversions of factor VIII, of the IDS gene and of the FLN1/emerin region, all resulting from misalignment of inverted repeats, and double recombination. Most of these inversions are of paternal origin possibly because the X chromosome at male meiosis is free to refold into itself for most of its length. We report on two de novo rearrangements of the X chromosome found in four hypogonadic females. Two of them had an X chromosome deleted for most of Xp and duplicated for a portion of Xq and two had the opposite rearrangement (class I and class II rearrangements, respectively). The breakpoints were defined at the level of contiguous YACs. The same Xp 11.23 breakpoint was found in the four cases. That of the long arm coincided in three cases (Xq21.3) and was more proximal in case 4 (Xq21.1). Thus class I rearrangements (cases 1 and 2) are reciprocal to that of case 3, whilst that of case 4 shares only the Xp breakpoint. The abnormal X was paternal in the three cases investigated. Repeated inverted sequences located at the breakpoints of rearrangements are likely to favour the refolding of the paternal X chromosome and the recombination of the repeats. The repeat at the Xp11 may synapse with either that at Xq21.3 or that at Xq21.1. These rearrangements seem to originate as the Xq28 submicroscopic inversions but they are identifiable at the microscopic level and result from a single recombination event.
Assuntos
Aberrações dos Cromossomos Sexuais/genética , Cromossomo X/genética , Adolescente , Adulto , Idoso , Amenorreia/genética , Southern Blotting , Quebra Cromossômica , Deleção Cromossômica , Cromossomos Artificiais de Levedura , Feminino , Duplicação Gênica , Transtornos do Crescimento/genética , Humanos , Hipogonadismo/genética , Hibridização in Situ Fluorescente , Masculino , Meiose/genética , Repetições de Microssatélites/genética , Linhagem , Recombinação Genética/genética , Sequências Repetitivas de Ácido NucleicoRESUMO
A new mutation in human F(1)F(0) ATPase6, T9176G, which changes Leu 217 to an Arg, has been described in two siblings with Leigh syndrome [Carrozzo et al. (2000) Neurology, in press]. This mutation was modeled in Escherichia coli by changing Leu 259 (the equivalent residue) to Arg and the properties of the altered ECF(1)F(0) were compared to those of previously characterized ATPase6 mutants also modeled in the E. coli enzyme. The L259R change produced a fully assembled ECF(1)F(0) which had no significant ATP hydrolysis, ATP synthesis or proton pumping functions. This is very different from previously described human ATPase6 mutations. The presence of Arg at position 259 in subunit a did not make membranes permeable to protons. We conclude that the mutation inhibits functioning by blocking the rotary motor action of the enzyme.
Assuntos
Adenosina Trifosfatases/genética , DNA Mitocondrial/genética , Escherichia coli/genética , Mutação Puntual/genética , ATPases Translocadoras de Prótons/genética , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Substituição de Aminoácidos , Western Blotting , Dicicloexilcarbodi-Imida/farmacologia , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/genética , Escherichia coli/enzimologia , Humanos , Hidrólise , Membranas/enzimologia , ATPases Mitocondriais Próton-Translocadoras , Proteínas Motores Moleculares/genética , NAD/metabolismo , NAD/farmacologia , ATPases Translocadoras de Prótons/metabolismoRESUMO
OBJECTIVE: To examine the clinical and MRI associations in bilateral periventricular nodular heterotopia (BPNH) (MIM # 300049) in two families segregating a missense mutation and a C-terminal deletion of the filamin 1(FLN1) gene. BACKGROUND: Classical familial BPNH, an X-linked dominant disorder, has been associated with protein truncations or splicing mutations, which tend to cluster at the N-terminal of the FLN1 protein, causing severe predicted loss of the protein function. The clinical syndrome includes symmetrical contiguous nodular heterotopia lining the lateral ventricles, epilepsy, mild retardation to normal cognitive level in affected females, and prenatal lethality in hemizygous boys. METHODS: Clinical examination, cognitive testing, MRI, mutation analysis (direct sequencing, single-strand conformation polymorphism) in seven patients from two families with BPNH. RESULTS: In Family 1, harboring an A > T change in exon 2 (E82V), heterotopic nodules were few, asymmetric, and noncontiguous. Five boys born from affected females had died unexpectedly early in life. In Family 2, harboring an 8 base pair deletion in exon 47 (7627_7634del TGTGCCCC), heterotopic nodules were thick and contiguous. Affected females in both families showed normal to borderline IQ and epilepsy. CONCLUSION: Missense mutations and distal truncations consistent with partial loss of FLN1 function cause familial BPNH with the classical clinical phenotype including epilepsy and mild mental retardation, if any. However, missense mutations have milder anatomic consequences in affected females and are possibly compatible with live birth but short survival of boys.
Assuntos
Córtex Cerebral , Coristoma/genética , Coristoma/patologia , Proteínas Contráteis/genética , Ventrículos Laterais/patologia , Proteínas dos Microfilamentos/genética , Mutação de Sentido Incorreto/genética , Aborto Espontâneo/genética , Aborto Espontâneo/patologia , Adolescente , Adulto , Sequência de Aminoácidos , Epilepsia/genética , Epilepsia/patologia , Feminino , Filaminas , Deleção de Genes , Humanos , Lactente , Recém-Nascido , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , LinhagemRESUMO
A family is described in which bilateral perisylvian polymicrogyria was present in 6 members of 3 consecutive generations. Typical anatomic and clinical findings of the syndrome, with a mild phenotype, were present in the 5 affected women from all 3 generations. More severe impairment was observed in the only affected male individual, a boy, in the third generation. Analysis of the pedigree and severity of the phenotype in the affected boy are consistent with transmission of an X-linked dominant trait, although other patterns of inheritance cannot be ruled out with certainty.
Assuntos
Córtex Cerebral/anormalidades , Epilepsia/genética , Epilepsia/fisiopatologia , Lateralidade Funcional/fisiologia , Adulto , Encéfalo/patologia , Encéfalo/fisiopatologia , Criança , Eletroencefalografia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , LinhagemRESUMO
Multiple mitochondrial DNA (mtDNA) deletions have been described in patients with autosomal dominant progressive external ophthalmoplegia (AD-PEO) and in autosomal recessive disorders including mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and autosomal recessive cardiomyopathy ophthalmoplegia (ARCO). The pathogenic bases of these disorders are unknown. We studied three patients with AD-PEO and three patients with autosomal recessive (AR)-PEO (two patients with MNGIE and one patient with ARCO). Histochemistry and Southern blot analyses of DNA were performed in skeletal muscle from the patients. Muscle mtDNA was used to characterize the pattern and amounts of the multiple mtDNA rearrangements; PCR analysis was performed to obtain finer maps of the deleted regions in both conditions. The patients with AD-PEO had myopathic features; the patients with AR-PEO had multisystem disorders. The percentage of ragged-red and cytochrome c oxidase-negative fibers tended to be higher in muscle from the patients with AD-PEO (19% +/- 13.9, 29.7 +/- 26.3) than in muscle from the patients with AR-PEO (1.4% +/- 1.4, 3.3% +/- 3.2; p < 0.10). The sizes of the multiple mtDNA deletions ranged from approximately 4.0 to 10.0 kilobases in muscle from both groups of patients, and in both groups, we identified only deleted and no duplicated mtDNA molecules. Patients with AD-PEO harbored a greater proportion of deleted mtDNA species in muscle (31% +/- 5.3) than did patients with AR-PEO (9.7% +/- 9.1; p < 0.05). In the patients with AD-PEO, we identified a deletion that included the mtDNA heavy strand promoter (HSP) region, which had been previously described as the HSP deletion. The HSP deletion was not present in the patients with AR-PEO. Our findings show the clinical, histologic, and molecular genetic heterogeneity of these complex disorders. In particular, the proportions of multiple mtDNA deletions were higher in muscle samples from patients with AD-PEO than in those from patients with AR-PEO.
Assuntos
DNA Mitocondrial/genética , Deleção de Genes , Encefalomiopatias Mitocondriais/genética , Oftalmoplegia/genética , Adulto , Biópsia , Southern Blotting , Aberrações Cromossômicas , Transtornos Cromossômicos , Citrato (si)-Sintase/metabolismo , DNA Mitocondrial/análise , Feminino , Genes Dominantes , Genes Recessivos , Heterogeneidade Genética , Humanos , Masculino , Pessoa de Meia-Idade , Encefalomiopatias Mitocondriais/etiologia , Encefalomiopatias Mitocondriais/patologia , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Oftalmoplegia/etiologia , Oftalmoplegia/patologia , Reação em Cadeia da PolimeraseRESUMO
The authors identified a novel mtDNA mutation (T9176G) in the ATPase 6 gene in a family in which a 10-year-old girl had a severe neurodegenerative disorder, her elder sister had died of Leigh syndrome (LS), and a maternal uncle had a spinocerebellar disorder. Biochemical studies disclosed a reduced rate of ATP synthesis in skin fibroblast cultures from the proposita as the likely explanation of her severe illness. The findings expand the genetic variants associated with LS.
Assuntos
Trifosfato de Adenosina/biossíntese , DNA Mitocondrial/genética , Doença de Leigh/etiologia , Doença de Leigh/genética , Mutação/genética , Criança , DNA Mitocondrial/metabolismo , Feminino , Humanos , LinhagemRESUMO
The authors describe a family of Sephardic Jews with progressive external ophthalmoparesis, skeletal muscle weakness, and parkinsonism. Autosomal recessive inheritance was suggested by many consanguineous marriages, although a dominant disorder could not be excluded. No linkage to known progressive external ophthalmoparesis locus was found. The presence of cytochrome c oxidase-negative ragged-red fibers, biochemically reduced respiratory chain complexes, and multiple mitochondrial DNA deletions in muscle biopsies from four patients suggested a new mitochondrial disorder of intergenomic communication.
Assuntos
DNA Mitocondrial/genética , Deleção de Genes , Miopatias Mitocondriais/genética , Doença de Parkinson/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Judeus , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/etnologia , Doença de Parkinson/etnologia , LinhagemRESUMO
In this study we comparatively analysed deltoid histochemistry, biochemistry and mitochondrial DNA (mtDNA) in two groups of ten sporadic ocular mitochondrial myopathies (OMM), respectively with and without ragged red fibres (RRF). (1) All but one RRF--patients presented the mild form of OMM with blepharoptosis but without ophthalmoplegia; (2) the occurrence of cytochrome c oxidase deficient (COX-) fibres was significantly higher in the RRF+ group, but four RRF- cases also showed COX- fibres; (3) no difference was observed in biochemical findings between the groups; (4) two RRF- patients without COX- fibres showed mtDNA heteroplasmy; (5) in two RRF- patients without deltoid mtDNA deletion, biopsy of an eyelid muscle showed significant mitochondrial alterations. These results suggest that the expression of a mitochondrial defect can vary and that the absence of RRF in a skeletal muscle biopsy does not necessarily rule out the diagnosis of OMM, if other data support that.
Assuntos
Blefaroptose/metabolismo , Mitocôndrias Musculares/metabolismo , Miopatias Mitocondriais/metabolismo , Oftalmoplegia Externa Progressiva Crônica/metabolismo , Adolescente , Adulto , Idoso , Blefaroptose/genética , Blefaroptose/patologia , Criança , DNA Mitocondrial/biossíntese , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mitocôndrias Musculares/enzimologia , Mitocôndrias Musculares/patologia , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/patologia , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Oxirredutases/metabolismo , FenótipoRESUMO
Cardiomyopathy associated with a mitochondrial DNA depletion syndrome is a rare condition. We report on a child with a hypertrophic cardiomyopathy and a mitochondrial depletion syndrome who was successfully treated by heart transplantation, given the tissue-specific nature of her mitochondrial disorder.