Caracterização da força e da função muscular nas disferlinopatias em amostra brasileira / Characterization of muscle strength and function in dysferlinopathy in a Brazilian sample

Estudo de caracterização da força e da função muscular nas disferlinopatias para estabelecer biomarcadores de habilidades motoras com amostra de 40 pacientes, tendo sido avaliados força muscular (Medical Research Council - MRC), percentual de MRC, tempo de execução para deambular e escores nas Escalas de Vignos, Egen Klassifikation, Avaliação Funcional para Distrofia Muscular de Duchenne (FES-DMD) e North Star Ambulatory Assessment adaptada. Prevalência da disferlinopatia de 25,5% na amostra total de distrofias (1340), idade média de 36,5 anos, 52,5% do sexo masculino e 75% deambuladores. Músculos mais fracos: abdominal, glúteos, íliopsoas, isquiotibial, quadríceps femoral, tibial anterior e deltoide médio. Correlação forte entre MRC e tempo para deambular (r = 0,77) e, muito forte da MRC distal de membros inferiores com aNSAA (r = 0,90). Interação da MRC dos membros superiores e inferiores nos segmentos proximal e distal (p < 0,001), sendo mais evidente em membros superiores que inferiores. Taxa variável de progressão da doença com 60% dos pacientes moderadamente ou gravemente afetados, com mais de 12 anos de doença. Estudo mostra que padrão de fraqueza muscular dos brasileiros com disferlinopatia é proximal e distal dos MMII, com comprometimento associado da região proximal dos MMSS, além de elucidar as habilidades motoras em relação ao processo de locomoção e disfunções cardiorrespiratórias. (AU).

Dysferlin Gene Mutation Spectrum in a Large Cohort of Chinese Patients with Dysferlinopathy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Dysferlinopathy is caused by mutations in the dysferlin (DYSF) gene. Here, we described the genetic features of a large cohort of Chinese patients with this disease.</p><p><b>METHODS</b>Eighty-nine index patients were included in the study. DYSF gene analysis was performed by Sanger sequencing in 41 patients and targeted next generation sequencing (NGS) in 48 patients. Multiplex ligation-dependent probe amplification (MLPA) was performed to detect exon duplication/deletion in patients with only one pathogenic mutation.</p><p><b>RESULTS</b>Among the 89 index patients, 79 patients were demonstrated to carry two disease-causing (73 cases) or possibly disease-causing mutations (6 cases), including 26 patients with homozygous mutations. We identified 105 different mutations, including 59 novel ones. Notably, in 13 patients in whom only one pathogenic mutation was initially found by Sanger sequencing or NGS, 3 were further identified to carry exon deletions by MLPA. The mutations identified in this study appeared to cluster in the N-terminal region. Mutation types included missense mutations (30.06%), nonsense mutations (17.18%), frameshift mutations (30.67%), in-frame deletions (2.45%), intronic mutations (17.79%), and exonic rearrangement (1.84%). No genotype-phenotype correlation was identified.</p><p><b>CONCLUSIONS</b>DYSF mutations in Chinese patients clustered in the N-terminal region of the gene. Exonic rearrangements were found in 23% of patients with only one pathogenic mutation identified by Sanger sequencing or NGS. The novel mutations found in this study greatly expanded the mutational spectrum of dysferlinopathy.</p>

Dysferlin deficiency: the cause of limb-girdle muscular dystrophy 2B and Miyoshi myopathy in a Chinese pedigree / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify an inbred Chinese pedigree with autosomal recessive muscular dystrophy and analyze the molecular defects.</p><p><b>METHODS</b>Linkage analysis was conducted using short tandem repeat(STR) markers from the regions associated with limb-girdle muscular dystrophy type 2A(LGMD2A) through 2H. Multi-Western blot was performed with anti-calpain-3, anti-dysferlin, anti-gamma-sarcoglycan, anti-alpha-sarcoglycan, and anti-dystrophin monoclonal antibodies. Mutation was determined by reverse transcriptase-polymerase chain reaction and sequencing.</p><p><b>RESULTS</b>Two-point linkage analysis showed significant Lod scores with markers from chromosome 2p13, the highest two-point Lod scores were obtained with D2S337 (Z(max)=1.86 at theta=0). Multi-Western blot confirmed dysferlin deficiency of muscle specimen from the proband. Mutation analysis revealed a novel 6429delG mutation on exon 53 of the DYSF gene for the proband.</p><p><b>CONCLUSION</b>The authors identified an inbred Chinese pedigree with Miyoshi myopathy caused by a 6429delG on the DYSF gene. This mutation is predicted to result in premature termination of translation.</p>