Dysferlin蛋白缺陷的Miyoshi肌病的临床与病理学特点

目的探讨dysferlin蛋白缺陷的Miyoshi肌病(MM)的临床与病理学特点。方法对3例MM患者的临床及病理资料进行分析。结果3例患者均为青少年起病,临床主要表现均为下肢远端无力伴肌肉明显萎缩,其中1例发病初期伴有小腿肌肉疼痛肿胀,1例下肢近端肌肉无力;3例患者血清肌酸磷酸激酶均明显升高,分别为7543IU/L、5657IU/L、8721IU/L;2例乳酸脱氢酶升高,分别为465IU/L、636IU/L。3例肌肉病理均为肌源性损害,肌细胞膜dysferlin蛋白明显缺失,dystrophin表达正常;其中1例肌肉病理有炎细胞浸润。结论MM患者均为青少年起病,临床以下肢无力及肌萎缩为特点,病理可见肌细胞膜dysferlin蛋白缺失。     

A novel compound heterozygous dysferlin mutation in Miyoshi myopathy siblings responding to dantrolene

Miyoshi myopathy (MM) is an autosomal recessive distal muscular dystrophy characterized by mutations of the dysferlin gene. Although several pairs of homozygous/heterozygous mutations have been reported, few effective treatments of MM are available. We had observed the decreased serum creatine kinase (CK) before and after administration of dantrolene in the elder brother and the increased serum CK before and after discontinuance of the drug on suspicion of drug-induced hepatopathy in the younger sister. We report a novel pair of heterozygous mutations in the 3'-splicing site of exon 26 and the translation site of exon 28 of the dysferlin gene in two siblings, and effective treatment of their MM with dantrolene.     

Dysferlin mutation analysis in a group of Italian patients with limb-girdle muscular dystrophy and Miyoshi myopathy

Mutations in the dysferlin gene (DYSF) on chromosome 2p13 cause distinct phenotypes of muscular dystrophy: limb-girdle muscular dystrophy type 2B (LGMD2B), Miyoshi myopathy (MM), and distal anterior compartment myopathy, which are known by the term 'dysferlinopathy'. We performed mutation analyses of DYSF in 14 Italian patients from 10 unrelated families with a deficiency of dysferlin protein below 20% of the value in normal controls by immunoblotting analysis. We identified 11 different mutations, including eight missense and three deletion mutations. Nine of them were novel mutations. We also identified a unique 6-bp insertion polymorphism within the coding region of DYSF in 15% of Italian population, which was not observed in East Asian populations. The correlation between clinical phenotype and the gene mutations was unclear, which suggested the role of additional genetic and epigenetic factors in modifying clinical symptoms.     

Abnormal expression of dysferlin in skeletal muscle and monocytes supports primary dysferlinopathy in patients with one mutated allele

Background: In some cases, a definitive confirmation of dysferlinopathy cannot be achieved by DNA test, because the mutation is detected in one allele only. Patients and methods: Dysferlin expression in skeletal muscle and peripheral blood monocytes (PBM) was studied by Western blot in two unrelated adult patients. The comparative C_T method (ΔΔC_T) was used to calculate relative changes in dysferlin mRNA determined from real‐time quantitative PCR experiments. The dysferlin gene was studied by direct sequencing of cDNA and genomic DNA and by Multiplex Ligation‐dependent Probe Amplification (MLPA) analysis. Results: A comparable severe reduction in dysferlin was demonstrated in both skeletal muscle and PBM. The expression of dysferlin mRNA was significantly reduced. A novel mutation in exon 47 (c.5289G>C) of the dysferlin gene in the heterozygous state, causing an amino acid change (p.Glu1763Asp), was detected in both patients. The MLPA analysis did not reveal any deletion or duplication. Conclusions: Dysferlin and/or dysferlin mRNA abnormalities are diagnostic for dysferlinopathy when mutational analysis detects a mutation in one allele only. Analysis of dysferlin mRNA can be helpful for distinguishing symptomatic heterozygotes from such patients.     

Late-onset distal myopathy with rimmed vacuoles without mutation in the GNE or dysferlin genes

We report two brothers from a Japanese family with a late-onset distal myopathy characterized by rimmed vacuoles and dysferlin deficiency with no inflammatory infiltration and dystrophic changes in muscle biopsy. Mutations in the GNE, dysferlin, caveolin 3, emerin, and lamin A/C genes were excluded. We speculate that dysferlin is involved in the pathogenesis of the myopathy in these patients, which may represent a new disease entity presenting as a distal myopathy.     

Muscle pathology in dysferlin deficiency

Dysferlin deficiency is being increasingly recognized in limb-girdle dystrophy and distal myopathy but its role in the development of muscle pathology is still poorly understood. For this purpose, 26 muscle biopsies from 25 dysferlinopathy patients were analysed by routine histochemistry and by immunohistochemistry with eight different antibodies, and scored for inflammatory response and type of cell infiltrate, fibre degeneration and regeneration, fibre type composition and severity of histopathological changes. In cases with an advanced-stage dystrophic pattern we observed type 1 fibre predominance exceeding 80%, suggesting a selective loss of type 2 fibres or a conversion process. The extent of muscle fibre regeneration and degeneration in dysferlinopathy was intermediate between sarcoglycanopathy and Duchenne dystrophy or myositis, suggesting a rather aggressive course of the disease. An increased inflammatory response was observed in the majority of our patients (16/26), who also showed an active dystrophic pattern. Type and localization of cellular infiltrates suggest that inflammatory reaction is secondary to necrosis. Major histocompatibility complex (MHC) class I molecules were overexpressed in dysferlinopathy, mainly in association with fibre phagocytosis and regeneration; their occasional expression in non-necrotic fibres might represent a marker of ongoing necrosis. Muscle inflammation might be triggered by the structurally altered membrane consequent to dysferlin defect.     

Genomic organization of the dysferlin gene and novel mutations in Miyoshi myopathy

OBJECTIVE: Mutations in the skeletal muscle gene dysferlin cause two autosomal recessive forms of muscular dystrophy: Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B). The purpose of this study was to define the genomic organization of the dysferlin gene and conduct mutational screening and a survey of clinical features in 21 patients with defined molecular defects in the dysferlin gene. METHODS: Genomic organization of the gene was determined by comparing the dysferlin cDNA and genomic sequence in P1-derived artificial chromosomes (PACs) containing the gene. Mutational screening entailed conformational analysis and sequencing of genomic DNA and cDNA. Clinical records of patients with defined dysferlin gene defects were reviewed retrospectively. RESULTS: The dysferlin gene encompasses 55 exons spanning over 150 kb of genomic DNA. Mutational screening revealed nine novel mutations associated with MM. The range of onset in this patient group was narrow with a mean of 19.0 +/- 3.9 years. CONCLUSION: This study confirms that the dysferlin gene is mutated in MM and LGMD2B and extends understanding of the timing of onset of the disease. Knowledge of the genomic organization of the gene will facilitate mutation detection and investigations of the molecular biologic properties of the dysferlin gene.     

Genetic fine mapping of the Miyoshi myopathy locus and exclusion of eight candidate genes

Miyoshi myopathy (MM) is an early adult-onset, autosomal recessive disorder characterized by weakness and muscular atrophy starting in the distal muscles. The disease locus has been previously mapped by linkage analysis to chromsome 2p using the microsatellite marker D2S291. Initial haplotype analysis of markers in families from three different origins (North American, Japanese, and Tunisian) suggested that the MM gene is located in a 4-cM region flanked by markers D2S292 on the telomeric side and D2S286 on the centromeric side. To delineate critical recombination events revealing a more refined localization of the MM gene, we have determined the pattern of segregation of 12 marker loci in two consanguineous families of Tunisian origin. In this study we have: (1) detected recombination events with the disease locus in one family, placing the MM gene most likely between markers D2S443 (CHLC.GGAA4D07.1876) and D2S2109; (2) generated a yeast artificial chromosome contig that spans approximately 3.8 megabases and extends from marker D2S358 to marker D2S286; (3) physically mapped 21 polymorphic markers, 5 genes, 3 STSs, and 1 EST within this contig; (4) detected and mapped a new polymorphism within this interval, allowing us to further reduce the MM locus to a 360-kilobase segment; (5) mapped the gene for the cytoskeletal protein β-adducin within the MM candidate region, failing to find a consistent pattern of mutation of this gene in our MM patients; (6) excluded seven other candidate myopathy genes from the Miyoshi locus. Accepted: August 14, 1997     

Novel FLNC mutation in a patient with myofibrillar myopathy in combination with late-onset cerebellar ataxia

Introduction: Mutations in the gene that encodes filamin C, FLNC, represent a rare cause of a distinctive type of myofibrillar myopathy (MFM). Methods: We investigated an Italian patient by means of muscle biopsy, muscle and brain imaging and molecular analysis of MFM genes. Results: The patient harbored a novel 7256C>T, p.Thr2419Met mutation in exon 44 of FLNC. Clinical, pathological and muscle MRI findings were similar to the previously described filaminopathy cases. This patient had, in addition, cerebellar ataxia with atrophy of cerebellum and vermis evident on brain MRI scan. Extensive screening failed to establish a cause of cerebellar atrophy. Conclusions: We report an Italian filaminopathy patient, with a novel mutation in a highly conserved region. This case raises the possibility that the disease spectrum caused by FLNC may include cerebellar dysfunction. Muscle Nerve 275–282, 2012     

Pure quadriceps myopathy in two sisters

The authors carried out a clinical, laboratory and muscle computed tomographgy CT follow-up study of 18-21 years on two sisters affected by quadriceps myopathy (QM). The onset in the fourth decade was a weakness in the thighs. During the follow-up study, the patients showed only vasti muscles involvement, normal creatine kinase (CK) levels, myopathic muscle biopsy and electromyography (EMG) and normal membrane protein expression on immunocytochemical analysis. Therefore, all muscle pathologies known to have quadriceps involvement as a leading feature have been ruled out. We conclude that our patients have pure QM with probable autosomal recessive inheritance.     

Comparing clinical data and muscle imaging of DYSF and ANO5 related muscular dystrophies

In this retrospective cross-sectional study clinical and muscle imaging data of patients with Miyoshi distal myopathy phenotype (MMD1 and MMD3) and limb girdle muscular dystrophy 2L (LGMD2L) were described. MMD1 and MMD3 are genetically heterogenous diseases based on DYSF and ANO5 gene defects. MMD3 and LGMD2L are clinically different diseases caused by an ANO5 gene defect. All groups showed predominant fatty degeneration of the gluteus minimus muscle and of the posterior segments of the thigh and calf muscles with sparing of the gracilis muscle. Muscle atrophy, hypertrophy and asymmetric muscle involvement on muscle imaging did not differ between groups. The pattern of fatty degeneration of muscles and of muscle weakness shows only minor differences between MMD1 (n = 6) and MMD3 (n = 8) patients with more frequently fatty degeneration of the rectus femoris, anterior tibial, and extensor digitorum muscles and more frequently muscle weakness in the anterior tibial, peroneal and calf muscle in MMD1. In the ANO5 related phenotypes the lateral head of the gastrocnemius muscle was less frequently involved in LGMD2L (n = 13) and no differences in the incidence of muscle weakness was found. Therefore, MMD3 and LGMD2L should be considered as part of one spectrum of ANO5 related muscle disease.     

Progress and challenges in diagnosis of dysferlinopathy

Dysferlin‐deficient limb girdle muscular dystrophy type 2B, distal Miyoshi myopathy, and other less frequent phenotypes are a group of recessive disorders called dysferlinopathies. They are characterized by wide clinical heterogeneity. To diagnose dysferlinopathy, a clinical neuromuscular workup, including electrophysiological and muscle imaging investigations, is essential to support subsequent laboratory testing. Increased serum creatine kinase levels, distal or proximal muscle weakness, and myalgia with onset in the second or third decades are the main clinical features of the disease. In muscle biopsies, severe dysferlin deficiency by immunoblot or its abnormal localization by immunohistochemistry are the gold standard, as they have a high diagnostic value. Dysferlin testing on monocytes is a valuable alternative to muscle immunoblotting. Molecular techniques for gene mutation detection, such as next generation sequencing, have improved the genetic diagnosis, which is crucial for treatment and genetic counselling. Muscle Nerve 54 : 821–835, 2016     

Nonaka肌病的GNE基因突变研究

目的报告2例Nonaka肌病的GNE基因突变特点。方法对2例经临床和病理检查证实的Nonaka 肌病,用PCR和DNA测序方法检测GNE基因编码区外显子及其侧翼序列,对例1家系中3代共7人也作该基因的突变检查。结果例1在GNE基因外显子8出现1 525C→T纯合突变;例2在外显子2出现527A→T杂合突变和外显子9出现1714G→C杂合突变,上述突变分别造成GNE出现H509Y的纯合突变以及D176V和V572L的复合杂合突变。例1的家系中患者的父母分别为H509Y的杂合突变。结论我们这2例Nonaka肌病患者的发病均是由GNE 基因突变所致,其中H509Y突变为新发现的突变类型。同时也证实我国Nonaka肌病也存在日本患者GNE的热点突变。     

Collagen XII myopathy with rectus femoris atrophy and collagen XII retention in fibroblasts

Introduction: Mutation in the collagen XII gene (COL12A1) was recently reported to induce Bethlem myopathy. We describe a family affected by collagen XII‐related myopathy in 3 generations. Methods: Systematic interview, clinical examination, skin biopsies, and MRI of muscle were used. Results: The phenotype was characterized by neonatal hypotonia, contractures, and delayed motor development followed by resolution of contractures and a motor performance limited by reduced endurance. DNA analyses revealed a novel donor splice‐site mutation in COL12A1 (c.8100 + 2T>C), which segregated with clinical affection and abnormal collagen XII retention in fibroblasts. MRI disclosed a selective wasting of the rectus femoris muscle. Discussion: COL12A1 mutations should be considered in patients with a mild Bethlem phenotype who present with selective wasting of the rectus femoris, absence of the outside‐in phenomenon on MRI, and abnormal collagen XII retention in fibroblasts. Muscle Nerve 57 : 1026–1030, 2018     

Open muscle biopsy in suspected myopathy: diagnostic yield and clinical utility

Background:  The purpose of the study was to investigate the diagnostic yield and clinical utility of open muscle biopsy and to identify pre-biopsy factors that might predict useful clinical results for suspected myopathy.
Methods:  Two-hundred fifty-eight muscle biopsies, performed for investigation of suspected myopathy, were evaluated.
Results:  A specific clinical diagnosis following muscle biopsy was made in 43% of cases. As a result of the biopsy, clinical diagnosis was changed in 47% and treatment was changed in 33% of cases. Results either led to a specific clinical diagnosis or changed the diagnosis/treatment in 74% of patients. Positive family history of myopathy and findings of myopathic irritability on electromyography had a negative predictive value for diagnosis change.
Conclusions:  Open muscle biopsy is useful in myopathy evaluation in the modern genetic era.     

Novel DYSF mutations in Thai patients with distal myopathy

Dysferlinopathy refers to a variety of autosomal recessive, skeletal muscle disorders due to the mutations of dysferlin-encoding gene, DYSF. It encompasses limb-girdle muscular dystrophy type 2B (LGMD2B), Miyoshi myopathy (MM), distal myopathy with anterior tibial onset (DMAT), isolated hyperCKemia, rigid spine syndrome and congenital muscular dystrophy. Herein, we report five Thai patients with distal myopathy due to dysferlinopathy including four MM and one DMAT patients. Muscle biopsy from one MM patient depicted numerous ring fibers which is an atypical finding in dysferlinopathy. Mutation analysis of DYSF revealed novel compound heterozygous mutations of p.Tyr309X and c.236 + 1G > T in two related MM patients, known homozygous mutations, p.Arg89X and p.Gln176X, in two MM patients and a heterozygous missense mutation, p.Arg555Trp, in a DMAT patient. Most of the previously reported DMAT patients were Hispanic. To the best of our knowledge, this is the first report of genetically confirmed patients with dysferlinopathy in Thailand.     

Multiple sclerosis and mitochondrial myopathy: An unusual combination of diseases

A woman with definite multiple sclerosis (MS) and mitochondrial myopathy is described. There were widespread white matter lesions on magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) abnormalities and evoked response changes. Muscle biopsy showed ragged red fibres (RRFs) and cytochrome c oxidase (CoX) deficiency. Southern blot analysis revealed a large deletion of mitochondrial DNA (mtDNA). The patient may be affected by two unrelated diseases, MS and mitochondrial myopathy, but this combination has never previously been reported.