China ; Dysferlin/genetics* ; Humans ; Muscular Dystrophies, Limb-Girdle/genetics* ; Mutation

OBJECTIVETo identify an inbred Chinese pedigree with autosomal recessive muscular dystrophy and analyze the molecular defects.

METHODSLinkage 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.

RESULTSTwo-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.

CONCLUSIONThe 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.

DNA, Complementary ; chemistry ; Dysferlin ; Genetic Linkage ; Humans ; Male ; Membrane Proteins ; genetics ; Middle Aged ; Muscle Proteins ; genetics ; Muscular Diseases ; genetics ; Muscular Dystrophies ; genetics ; Mutation ; Pedigree

BACKGROUNDDysferlinopathy 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.

METHODSEighty-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.

RESULTSAmong 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.

CONCLUSIONSDYSF 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.

Adolescent ; Adult ; Asian Continental Ancestry Group ; Child ; China ; Codon, Nonsense ; genetics ; Dysferlin ; Exons ; genetics ; Female ; Frameshift Mutation ; genetics ; Gene Frequency ; genetics ; Genotype ; High-Throughput Nucleotide Sequencing ; Humans ; Male ; Membrane Proteins ; genetics ; Middle Aged ; Muscle Proteins ; genetics ; Muscular Dystrophies, Limb-Girdle ; genetics ; Mutation ; genetics ; Mutation, Missense ; genetics ; Phenotype ; Young Adult