RESUMO
OBJECTIVE: Mitochondrial myopathy without extraocular muscles involvement (MiMy) represents a distinct form of mitochondrial disorder predominantly affecting proximal/distal or axial muscles, with its phenotypic, genotypic features, and long-term prognosis poorly understood. METHODS: A cross-sectional study conducted at a national diagnostic center for mitochondrial disease involved 47 MiMy patients, from a cohort of 643 mitochondrial disease cases followed up at Qilu Hospital from January 1, 2000, to January 1, 2021. We compared the clinical, pathological, and genetic features of MiMy to progressive external ophthalmoplegia (PEO) and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) patients. RESULTS: MiMy patients demonstrated a more pronounced muscle involvement syndrome, with lower 6MWT scores, higher FSS, and lower BMI compared to PEO and MELAS patients. Serum levels of creatinine kinase (CK), lactate, and growth and differentiation factor 15 (GDF15) were substantially elevated in MiMy patients. Nearly a third (31.9%) displayed signs of subclinical peripheral neuropathy, mostly axonal neuropathy. Muscle biopsies revealed that cytochrome c oxidase strong (COX-s) ragged-red fibers (RRFs) were a typical pathological feature in MiMy patients. Genetic analysis predominantly revealed mtDNA point pathogenic variants (59.6%) and less frequently single (12.8%) or multiple (4.2%) mtDNA deletions. During the follow-up, a majority (76.1%) of MiMy patients experienced stabilization or improvement after therapeutic intervention. CONCLUSIONS: This study provides a comprehensive profile of MiMy through a large patient cohort, elucidating its unique clinical, genetic, and pathological features. These findings offer significant insights into the diagnostic and therapeutic management of MiMy, ultimately aiming to ameliorate patient outcomes and enhance the quality of life.
Assuntos
Acidose Láctica , Síndrome MELAS , Oftalmoplegia Externa Progressiva Crônica , Acidente Vascular Cerebral , Humanos , Síndrome MELAS/genética , Músculos Oculomotores , Estudos Transversais , Qualidade de Vida , Acidente Vascular Cerebral/patologia , DNA Mitocondrial/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologiaRESUMO
BACKGROUND: Progressive external ophthalmoplegia (PEO) is a common subtype of mitochondrial encephalomyopathy. OBJECTIVE: The study aimed to investigate the relationship between mitochondrial DNA (mtDNA) abnormalities, muscle pathology, and clinical manifestations in Chinese patients with single large-scale mtDNA deletion presenting with PEO. METHODS: This is a retrospective single-center study. Patients with PEO who had a single large deletion in mitochondrial DNA were included in this study. The associations were analyzed between mtDNA deletion patterns, myopathological changes, and clinical characteristics. RESULTS: In total, 155 patients with mitochondrial PEO carrying single large-scale mtDNA mutations were enrolled, including 137 chronic progressive external ophthalmoplegia (CPEO) and 18 Kearns-Sayre syndrome (KSS) patients. The onset ages were 9.61 ± 4.12 in KSS and 20.15 ± 9.06 in CPEO. The mtDNA deletions ranged from 2225 bp to 9131 bp, with m.8470_13446del being the most common. The KSS group showed longer deletions than the CPEO group (p = 0.004). Additionally, a higher number of deleted genes encoding respiratory chain complex subunits (p = 0.001) and tRNA genes (p = 0.009) were also observed in the KSS group. A weak negative correlation between the mtDNA deletion size and ages of onset (p < 0.001, r = -0.369) was observed. The proportion of ragged red fibers, ragged blue fibers, and cytochrome c negative fibers did not correlate significantly with onset ages (p > 0.05). However, a higher percentage of abnormal muscle fibers corresponds to an increased prevalence of exercise intolerance, limb muscle weakness, dysphagia, and cerebellar ataxia. CONCLUSION: We reported a large Chinese cohort consisting of mitochondrial PEO patients with single large-scale mtDNA deletions. Our results demonstrated that the length and locations of mtDNA deletions may influence onset ages and clinical phenotypes. The severity of muscle pathology could not only indicate diagnosis but also may be associated with clinical manifestations beyond the extraocular muscles.
Assuntos
Síndrome de Kearns-Sayre , Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Humanos , Estudos Retrospectivos , Deleção de Genes , Oftalmoplegia/genética , Síndrome de Kearns-Sayre/genética , Síndrome de Kearns-Sayre/patologia , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/patologia , DNA Mitocondrial/genética , ChinaRESUMO
Genetic variation at HNRNPA2B1 is associated with inclusion body myopathy, Paget's disease and paediatric onset oculopharyngeal muscular dystrophy. We present a pedigree where a mother and two daughters presented with adolescent to early-adulthood onset of symptoms reminiscent of oculopharyngeal muscular dystrophy or chronic progressive external ophthalmoplegia, with a later limb-girdle pattern of weakness. Creatine Kinase was â¼1000 U/L. Myoimaging identified fatty replacement of sartorius, adductors longus and magnus, biceps femoris, semitendinosus and gastrocnemii. Muscle biopsies showed a variation of fibre size, occasional rimmed vacuoles and increased internalised myonuclei. Cases were heterozygous for a frameshift variant at HNRNPA2B1, consistent with a dominant and fully-penetrant mode of inheritance. Genetic variation at HNRNPA2B1 should be considered in adults with an oculopharyngeal muscular dystrophy-like or chronic progressive external ophthalmoplegia-like myopathy where initial testing fails to identify a cause.
Assuntos
Doenças Musculares , Distrofia Muscular Oculofaríngea , Oftalmoplegia Externa Progressiva Crônica , Adolescente , Adulto , Criança , Humanos , Músculo Esquelético/patologia , Doenças Musculares/genética , Distrofia Muscular Oculofaríngea/diagnóstico , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/patologia , Oftalmoplegia Externa Progressiva Crônica/patologia , Linhagem , FenótipoRESUMO
Progressive external ophthalmoplegia is a slowly progressive hereditary mitochondrial myopathy. Most mitochondrial disorders overlap clinically, enzymatically, and genetically. The most common enzyme defect is the combined deficit of complexes I and IV. Progressive external ophthalmoplegia particularly affects the extraocular muscles and is characterised by ophthalmoplegia, and bilateral ptosis. The ptosis and ophthalmoplegia is unresponsive to anticholinergics, with no effective treatment, but corrective surgery for ptosis as a palliative one. In this article, we report a rare case of a 16-year-old female with characterstic histological features consistent with progressive external ophthalmoplegia.
Assuntos
Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Feminino , Humanos , Adolescente , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Oftalmoplegia/diagnóstico , Oftalmoplegia/etiologia , Músculos Oculomotores/patologiaRESUMO
Bilateral lower extremity weakness and swelling can have several causes. Although often underdiagnosed, mitochondrial myopathy is more prevalent in the general population than more commonly suspected diseases, such as Guillain-Barre syndrome. The clinical manifestations of mitochondrial disease can be broadly classified into 3 categories: chronic progressive external ophthalmoplegia, skeletal muscle-central nervous system syndromes, or pure myopathy. Cardiac abnormalities occur in 30% to 32% of cases, mostly in the form of hypertrophic cardiomyopathy, dilated cardiomyopathy, or conduction abnormalities. We report a case of a 21-year-old student who developed bilateral lower limb weakness, pain, and swelling diagnosed with mitochondrial myopathy on muscle biopsy. Initial laboratory tests revealed elevated creatinine kinase, brain natriuretic peptide, troponin, myoglobin, and lactic acid and reduced serum bicarbonate. Cardiac workup revealed systolic heart failure with a reduced ejection fraction. Endomyocardial biopsy revealed punctate foci of lymphocytic myocarditis. However, cardiac magnetic resonance imaging did not reveal either myocarditis or an infiltrative cardiac disease. An extensive autoimmune and infection work-up was negative. A muscle biopsy from the patient's rectus femoris revealed scattered ragged-blue fibers (stained with NADH dehydrogenase), scattered ragged-red fibers on modified Gomori trichrome stain, and cytochrome-c oxidase negative fibers with increased perimysial and endomysial connective tissue, consistent with active and chronic primary mitochondrial myopathy. The patient was treated successfully with furosemide, metoprolol, and methylprednisolone. Adult-onset mitochondrial myopathy is a rare clinical disorder, and our experience stresses the importance of using an inter-disciplinary team approach to diagnose uncommon clinical disorders with widely variable multisystem involvement.
Assuntos
Miopatias Mitocondriais , Miocardite , Oftalmoplegia Externa Progressiva Crônica , Adulto , Masculino , Humanos , Adulto Jovem , Miocardite/patologia , Miopatias Mitocondriais/complicações , Miopatias Mitocondriais/diagnóstico , Miopatias Mitocondriais/patologia , Músculo Esquelético/patologia , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/patologia , Extremidade Inferior/patologiaRESUMO
RRM2B encodes the p53-inducible small subunit (p53R2) of ribonucleotide reductase, a key protein for mitochondrial DNA (mtDNA) synthesis. Pathogenic variants in this gene result in familial mitochondrial disease in adults and children, secondary to a maintenance disorder of mtDNA. This study describes two patients, mother and son, with early-onset chronic progressive external ophthalmoplegia (PEO). Skeletal muscle biopsy from the latter was examined: cytochrome c oxidase (COX)-negative fibres were shown, and molecular studies revealed multiple mtDNA deletions. A next-generation sequencing gene panel for nuclear-encoded mitochondrial maintenance genes identified two unreported heterozygous missense variants (c.514 G > A and c.682 G > A) in the clinically affected son. The clinically affected mother harboured the first variant in homozygous state, and the clinically unaffected father harboured the remaining variant in heterozygous state. In silico analyses predicted both variants as deleterious. Cell culture studies revealed that patients' skin fibroblasts, but not fibroblasts from healthy controls, responded to nucleoside supplementation with enhanced mtDNA repopulation, thus suggesting an in vitro functional difference in patients' cells. Our results support the pathogenicity of two novel RRM2B variants found in two patients with autosomal recessive PEO with multiple mtDNA deletions inherited with a pseudodominant pattern.
Assuntos
Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Ribonucleotídeo Redutases , Adulto , Criança , Humanos , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Padrões de Herança , DNA Mitocondrial/genética , Ribonucleotídeo Redutases/genética , Proteínas de Ciclo Celular/genéticaRESUMO
Progressive external ophthalmoplegia (PEO), characterized by ptosis and impaired eye movements, is a clinical syndrome with an expanding number of etiologically distinct subtypes. Advances in molecular genetics have revealed numerous pathogenic causes of PEO, originally heralded in 1988 by the detection of single large-scale deletions of mitochondrial DNA (mtDNA) in skeletal muscle of people with PEO and Kearns-Sayre syndrome. Since then, multiple point variants of mtDNA and nuclear genes have been identified to cause mitochondrial PEO and PEO-plus syndromes, including mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and sensory ataxic neuropathy dysarthria ophthalmoplegia (SANDO). Intriguingly, many of those nuclear DNA pathogenic variants impair maintenance of the mitochondrial genome causing downstream mtDNA multiple deletions and depletion. In addition, numerous genetic causes of nonmitochondrial PEO have been identified.
Assuntos
Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Humanos , Oftalmoplegia Externa Progressiva Crônica/complicações , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , DNA Mitocondrial/genética , Oftalmoplegia/genética , Oftalmoplegia/patologia , Músculo Esquelético/patologia , SíndromeRESUMO
Chronic progressive external ophthalmoplegia (CPEO) plus syndrome due to pathogenic biallelic variants in TOP3A gene has been described in only one single patient. We report two adult siblings with c.614A>G (p.Asp205Gly) homozygous missense variant in the TOP3A gene who had CPEO plus syndrome.
Assuntos
Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Adulto , Humanos , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Mutação de Sentido Incorreto , Homozigoto , Oftalmoplegia/genética , DNA Mitocondrial/genéticaRESUMO
A 48-year-old Japanese male experienced slowly progressive diplopia. He had no family history and was negative for the edrophonium chloride test. Blood analysis showed elevated lactic acid and pyruvic acid levels, suggesting mitochondrial disease. A muscle biopsy from the biceps brachii was performed, but no pathological or genetical mitochondrial abnormalities were detected. Subsequently, he underwent muscle plication for diplopia in which the right inferior rectus muscle was biopsied. Genetic examination of genomic DNA extracted from the extraocular muscle tissue revealed multiple mitochondrial gene deletions, with a heteroplasmy rate of approximately 35%, resulting in the diagnosis of chronic progressive external ophthalmoplegia. In mitochondrial diseases, the tissue distribution of mitochondria with disease-associated variants in mtDNA should be noted, and it is important to select the affected muscle when performing a biopsy for an accurate diagnosis.
Assuntos
Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Masculino , Humanos , Pessoa de Meia-Idade , Músculos Oculomotores/patologia , Diplopia , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Músculo Esquelético/patologia , DNA Mitocondrial/genética , Biópsia , Oftalmoplegia/etiologia , Oftalmoplegia/genéticaRESUMO
Mitochondrial DNA deletions affect energy metabolism at tissue-specific and cell-specific threshold levels, but the pathophysiological mechanisms determining cell fate remain poorly understood. Chronic progressive external ophthalmoplegia (CPEO) is caused by mtDNA deletions and characterized by a mosaic distribution of muscle fibers with defective cytochrome oxidase (COX) activity, interspersed among fibers with retained functional respiratory chain. We used diagnostic histochemistry to distinguish COX-negative from COX-positive fibers in nine muscle biopsies from CPEO patients and performed laser capture microdissection (LCM) coupled to genome-wide gene expression analysis. To gain molecular insight into the pathogenesis, we applied network and pathway analysis to highlight molecular differences of the COX-positive and COX-negative fiber transcriptome. We then integrated our results with proteomics data that we previously obtained comparing COX-positive and COX-negative fiber sections from three other patients. By virtue of the combination of LCM and a multi-omics approach, we here provide a comprehensive resource to tackle the pathogenic changes leading to progressive respiratory chain deficiency and disease in mitochondrial deletion syndromes. Our data show that COX-negative fibers upregulate transcripts involved in translational elongation and protein synthesis. Furthermore, based on functional annotation analysis, we find that mitochondrial transcripts are the most enriched among those with significantly different expression between COX-positive and COX-negative fibers, indicating that our unbiased large-scale approach resolves the core of the pathogenic changes. Further enrichments include transcripts encoding LIM domain proteins, ubiquitin ligases, proteins involved in RNA turnover, and, interestingly, cell cycle arrest and cell death. These pathways may thus have a functional association to the molecular pathogenesis of the disease. Overall, the transcriptome and proteome show a low degree of correlation in CPEO patients, suggesting a relevant contribution of post-transcriptional mechanisms in shaping this disease phenotype.
Assuntos
DNA Mitocondrial/genética , Mitocôndrias Musculares/genética , Fibras Musculares Esqueléticas/patologia , Oftalmoplegia Externa Progressiva Crônica/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Humanos , Microdissecção e Captura a Laser , Masculino , Mitocôndrias Musculares/patologia , NADPH Desidrogenase/genética , NADPH Desidrogenase/metabolismo , Oftalmoplegia Externa Progressiva Crônica/patologia , Proteômica/métodos , Succinato Desidrogenase/metabolismoRESUMO
Horizontal Gaze Palsy with Progressive Scoliosis-2 with Impaired Intellectual Development (HGPPS2) is a rare congenital disorder characterized by absence of conjugate horizontal eye movements, and progressive scoliosis developing in childhood and adolescence. We report three new patients with HGPPS2 in a consanguineous Pakistani family, presenting varying degrees of progressive scoliosis, developmental delays, horizontal gaze palsy, agenesis of corpus callosum, and absence of cerebral commissures. Analysis of genotyping data identified shared loss of heterozygosity (LOH) region on chromosomes 5p15.33-15.31, 6q11.2-12, and 18q21.1-21.3. A hypothesis-free, unbiased exome data analysis detected an insertion of nucleotide A (c.2399dupA) in exon 16 of the DCC gene. The insertion is predicted to cause frameshift p.(Asn800Lysfs*11). Interestingly, DCC gene is present in the LOH region on chromosome 18. Variant (c.2399dupA) in the DCC gene is considered as the most probable candidate variant for HGPPS2 based on the presence of DCC in the LOH region, previously reported role of DCC in HGPPS2, perfect segregation of candidate variant with the disease, prediction of variant pathogenicity, and absence of variant in variation databases. Sanger Sequencing confirmed the presence of the novel homozygous mutation in all three patients; the parents were heterozygous carriers of the mutation, in accordance with an autosomal recessive inheritance pattern. DCC encodes a netrin-1 receptor protein; its role in the development of the CNS has recently been established. Biallelic DCC mutations have previously been shown to cause HGPPS2. A novel homozygous variant in patients of the reported family extend the genotypic and phenotypic spectrum of HGPPS2.
Assuntos
Receptor DCC/genética , Predisposição Genética para Doença , Deficiência Intelectual/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Escoliose/genética , Adolescente , Adulto , Criança , Pré-Escolar , Consanguinidade , Feminino , Mutação da Fase de Leitura/genética , Genes Recessivos/genética , Homozigoto , Humanos , Deficiência Intelectual/complicações , Deficiência Intelectual/patologia , Masculino , Oftalmoplegia Externa Progressiva Crônica/complicações , Oftalmoplegia Externa Progressiva Crônica/patologia , Paquistão/epidemiologia , Linhagem , Escoliose/complicações , Escoliose/patologia , Adulto JovemRESUMO
Primary mitochondrial myopathies (PMM) are a group of mitochondrial disorders characterized by a predominant skeletal muscle involvement. The aim of this study was to evaluate whether the biochemical profile determined by Fourier-transform infrared (FTIR) spectroscopic technique would allow to distinguish among patients affected by progressive external ophthalmoplegia (PEO), the most common PMM presentation, oculopharyngeal muscular dystrophy (OPMD), and healthy controls. Thirty-four participants were enrolled in the study. FTIR spectroscopy was found to be a sensitive and specific diagnostic marker for PEO. In particular, FTIR spectroscopy was able to distinguish PEO patients from those affected by OPMD, even in the presence of histological findings similar to mitochondrial myopathy. At the same time, FTIR spectroscopy differentiated single mtDNA deletion and mutations in POLG, the most common nuclear gene associated with mitochondrial diseases, with high sensitivity and specificity. In conclusion, our data suggest that FTIR spectroscopy is a valuable biodiagnostic tool for the differential diagnosis of PEO with a high ability to also distinguish between single mtDNA deletion and mutations in POLG gene based on specific metabolic transitions.
Assuntos
DNA Mitocondrial/genética , Músculo Deltoide/química , Miopatias Mitocondriais/diagnóstico , Espectroscopia de Infravermelho com Transformada de Fourier , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Criança , DNA Polimerase gama/genética , DNA Mitocondrial/análise , Músculo Deltoide/patologia , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/patologia , Distrofia Muscular Oculofaríngea/diagnóstico , Distrofia Muscular Oculofaríngea/patologia , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/patologia , Sensibilidade e Especificidade , Adulto JovemRESUMO
No disponible
Assuntos
Humanos , Masculino , Pessoa de Meia-Idade , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Deleção de Genes , Testes de Função Respiratória , DNA Mitocondrial , Testes GenéticosRESUMO
Kearns-Sayre Syndrome (KSS) is a severe mitochondrial disorder involving the central nervous system, eyes, ears, skeletal muscles, and heart. The mitochondrial DNA (mtDNA) rearrangements, especially the deletions, are present in almost all KSS patients and considered as the disease-causing factor. However, the size and position of mtDNA deletions are distinct in different individuals. In this study, we report the case of a pair of Chinese twins with KSS. The twin patients revealed typical KSS clinical symptoms, including heart block, bilateral sensorineural hearing loss, progressive external ophthalmoplegia, exercise intolerance, proximal limb weakness, and endocrine disorders. Using long-range polymerase chain reactions (long-range PCR) and next-generation sequencing (NGS), the genetic features of the twin patients were investigated. A large 6600 bp mtDNA deletion, ranging from position 8702 to 15,302, was detected in both patients. To our knowledge, this kind of mtDNA deletion has never been described previously. Our study enriched the mutation spectrum of KSS and showed that NGS is a powerful tool for detecting mtDNA large variants.
Assuntos
DNA Mitocondrial/genética , Doenças em Gêmeos/genética , Síndrome de Kearns-Sayre/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Sistema Nervoso Central/patologia , Criança , Cromossomos/genética , Doenças em Gêmeos/patologia , Orelha/patologia , Olho/patologia , Deleção de Genes , Predisposição Genética para Doença , Coração/fisiopatologia , Humanos , Síndrome de Kearns-Sayre/patologia , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Mutação/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , FenótipoRESUMO
Biallelic mutations in the C1QBP gene have been associated with mitochondrial cardiomyopathy and combined respiratory-chain deficiencies, with variable onset (including intrauterine or neonatal forms), phenotypes, and severity. We studied two unrelated adult patients from consanguineous families, presenting with progressive external ophthalmoplegia (PEO), mitochondrial myopathy, and without any heart involvement. Muscle biopsies from both patients showed typical mitochondrial alterations and the presence of multiple mitochondrial DNA deletions, whereas biochemical defects of the respiratory chain were present only in one subject. Using next-generation sequencing approaches, we identified homozygous mutations in C1QBP. Immunoblot analyses in patients' muscle samples revealed a strong reduction in the amount of the C1QBP protein and varied impairment of respiratory chain complexes, correlating with disease severity. Despite the original study indicated C1QBP mutations as causative for mitochondrial cardiomyopathy, our data indicate that mutations in C1QBP have to be considered in subjects with PEO phenotype or primary mitochondrial myopathy and without cardiomyopathy.
Assuntos
Proteínas de Transporte , Miopatias Mitocondriais , Proteínas Mitocondriais , Oftalmoplegia Externa Progressiva Crônica , Oftalmoplegia , Proteínas de Transporte/genética , DNA Mitocondrial/genética , Homozigoto , Humanos , Miopatias Mitocondriais/genética , Proteínas Mitocondriais/genética , Mutação , Oftalmoplegia/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologiaRESUMO
BACKGROUND: Mitochondrial progressive external ophthalmoplegia (PEO) encompasses a broad spectrum of clinical and genetic disorders. We describe the phenotypic subtypes of PEO and its correlation with molecular defects and propose a diagnostic algorithm. METHODS: Retrospective analysis of the clinical, pathological and genetic features of 89 cases. RESULTS: Three main phenotypes were found: 'pure PEO' (42%), consisting of isolated palpebral ptosis with ophthalmoparesis; Kearns-Sayre syndrome (10%); and 'PEO plus', which associates extraocular symptoms, distinguishing the following subtypes: : myopathic (33%), bulbar (12%) and others (3%). Muscle biopsy was the most accurate test, showing mitochondrial changes in 95%. Genetic diagnosis was achieved in 96% of the patients. Single large-scale mitochondrial DNA (mtDNA) deletion was the most frequent finding (63%), followed by multiple mtDNA deletions (26%) due to mutations in TWNK (n=8), POLG (n=7), TK2 (n=6) or RRM2B (n=2) genes, and point mtDNA mutations (7%). Three new likely pathogenic mutations were identified in the TWNK and MT-TN genes. CONCLUSIONS: Phenotype-genotype correlations cannot be brought in mitochondrial PEO. Muscle biopsy should be the first step in the diagnostic flow of PEO when mitochondrial aetiology is suspected since it also enables the study of mtDNA rearrangements. If no mtDNA deletions are identified, whole mtDNA sequencing should be performed.
Assuntos
Proteínas de Ciclo Celular/genética , DNA Helicases/genética , DNA Polimerase gama/genética , Mitocôndrias/genética , Proteínas Mitocondriais/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Ribonucleotídeo Redutases/genética , Adolescente , Biópsia , Criança , Pré-Escolar , DNA Mitocondrial/genética , Feminino , Humanos , Lactente , Recém-Nascido , Síndrome de Kearns-Sayre/genética , Síndrome de Kearns-Sayre/patologia , Masculino , Mitocôndrias/patologia , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Oftalmoplegia Externa Progressiva Crônica/patologia , Fenótipo , Mutação Puntual/genética , Timidina QuinaseRESUMO
Mitochondrial encephalomyopathies comprise a group of heterogeneous disorders resulting from impaired oxidative phosphorylation (OxPhos). Among a variety of symptoms progressive external ophthalmoplegia (PEO) seems to be the most common. The aim of this study is to present clinical and genetic characteristics of Polish patients with PEO. Clinical, electrophysiological, neuroradiological, and morphological data of 84 patients were analyzed. Genetic studies of mitochondrial DNA (mtDNA) were performed in all patients. Among nuclear DNA (nDNA) genes POLG was sequenced in 41 patients, TWNK (C10orf2) in 13 patients, and RNASEH1 in 2 patients. Total of 27 patients were included in the chronic progressive external ophthalmoplegia (CPEO) group, 24 in the CPEO+ group. Twenty-six patients had mitochondrial encephalomyopathy (ME), six patients Kearns-Sayre syndrome (KSS), and one patient sensory ataxic neuropathy, dysarthria, ophthalmoparesis (SANDO) syndrome. Genetic analysis of nDNA genes revealed the presence of pathogenic or possibly pathogenic variants in the POLG gene in nine patients, the TWNK gene in five patients and the RNASEH1 gene in two patients. Detailed patients' history and careful assessment of family history are essential in the diagnostic work-up. Genetic studies of both mtDNA and nDNA are necessary for the final diagnosis of progressive external ophthalmoplegia and for genetic counseling.
Assuntos
DNA Helicases/genética , DNA Polimerase gama/genética , Síndrome de Kearns-Sayre/genética , Doenças Mitocondriais/genética , Encefalomiopatias Mitocondriais/genética , Proteínas Mitocondriais/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Ribonuclease H/genética , Adolescente , Adulto , Idoso , Cerebelo/diagnóstico por imagem , Cerebelo/metabolismo , Cerebelo/patologia , Cérebro/diagnóstico por imagem , Cérebro/metabolismo , Cérebro/patologia , Criança , DNA Helicases/metabolismo , DNA Polimerase gama/metabolismo , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Diagnóstico Diferencial , Feminino , Expressão Gênica , Humanos , Síndrome de Kearns-Sayre/diagnóstico por imagem , Síndrome de Kearns-Sayre/metabolismo , Síndrome de Kearns-Sayre/patologia , Masculino , Pessoa de Meia-Idade , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doenças Mitocondriais/diagnóstico por imagem , Doenças Mitocondriais/metabolismo , Doenças Mitocondriais/patologia , Encefalomiopatias Mitocondriais/diagnóstico por imagem , Encefalomiopatias Mitocondriais/metabolismo , Encefalomiopatias Mitocondriais/patologia , Proteínas Mitocondriais/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Oftalmoplegia Externa Progressiva Crônica/diagnóstico por imagem , Oftalmoplegia Externa Progressiva Crônica/metabolismo , Oftalmoplegia Externa Progressiva Crônica/patologia , Linhagem , Polônia , Polimorfismo Genético , Ribonuclease H/metabolismo , Deleção de SequênciaRESUMO
Chronic progressive external ophthalmoplegia (CPEO) is one of the most common mitochondrial disorders. It is characterized by bilateral, slowly progressing loss of extraocular muscle mobility, orbicularis oculi weakness, ptosis, and other neuromuscular symptoms, which are caused by the accumulation of multiple mitochondrial DNA (mtDNA) deletions. Many mutations in different nuclear genes, such as POLG1, POLG2, ANT1, and others, have been described as causing autosomal-inherited CPEO with multiple mtDNA deletions. Most causative genes are involved in mtDNA replication impairment. Here, we report a family with CPEO-like symptoms characterized by multiple muscle mtDNA deletions, ptosis, diabetes, hearing loss, mental retardation, and emotional instability. We performed genetic analyses to identify nuclear gene mutations in the family. DNA from the proband was analyzed by whole-exome sequencing. In addition to possible pathogenic mutations, rare variants were prioritized for gene-functional phenotype interpretation. We found possible pathogenetic mutations in the PRIMPOL, BRCA1, CPT2, and GJB2 genes, and functional polymorphisms in the CARD8, and MEFV genes. Multiple functional polymorphisms and possible pathogenic mutations may contribute to mitochondrial-disease-like phenotypes in a composite manner.
Assuntos
DNA Primase , DNA Polimerase Dirigida por DNA , Variação Genética , Enzimas Multifuncionais , Mutação , Oftalmoplegia Externa Progressiva Crônica , Fenótipo , Proteínas Adaptadoras de Sinalização CARD/genética , DNA Primase/genética , DNA Polimerase Dirigida por DNA/genética , Humanos , Mitocôndrias/genética , Enzimas Multifuncionais/genética , Mutação/genética , Proteínas de Neoplasias/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmoplegia Externa Progressiva Crônica/patologia , Polimorfismo Genético , Pirina/genética , Sequenciamento do ExomaRESUMO
Mitochondriopathies are a heterogeneous group of genetic diseases of all ages, with a very diverse clinical presentation related to genetic heteroplasmy. The clinical symptoms display a large variability and generally, the more severe phenotypes have an early onset, even from the neonatal period, while milder ones are manifested later in the adulthood. Most publications have already demonstrated deletions or point mutations in mitochondrial deoxyribonucleic acid (DNA), but in recent years, the field of investigation has expanded to syndromes caused by mutations in the nuclear DNA (nDNA), with a Mendelian inheritance. We present the case of a male patient with a mitochondriopathy with phenotype of chronic progressive external ophthalmoplegia (PEO), due to an autosomal dominant mutation in nDNA, in the DNA polymerase subunit gamma (POLG) gene, the pathogenic variant c.2864A>G (p.Tyr955Cys), morphologically investigated and diagnosed using a skeletal muscle biopsy. The aim of this presentation is to emphasize the diagnostic value of the muscle biopsy both in cases of clinical suspicion and in more challenging cases of mitochondrial diseases with atypical or unusual features. Although genetic testing may be the initial test of choice in cases with suggestive clinical presentation, muscle biopsy is an alternative diagnostic aid with high value even in our molecular era. We present pathological and ultrastructural data to confirm the diagnosis.