Genetic variability in Iranian limb-girdle muscular dystrophy type 2B patients: An evidence of a founder effect

Dysferlinopathies are a group of autosomal recessive limb-girdle muscular dystrophies (LGMDs) caused by mutations in DYSF (#603,009). This gene encodes a transmembrane protein called dysferlin. Since there are few reports on Iranian dysferlinopathy patients, we tried to identify the DYSF mutations in affected individuals of Iran.

Eight unrelated Iranian families have been selected for this study. Sanger sequencing followed by haplotype analysis was performed to identify individual variations in DYSF sequence. Identified variants were analyzed, and their pathogenicity was interpreted according to the recommendations of the American College of Medical Genetics and Genomics.

We identified two new mutations in DYSF, the first one is a nonsense mutation c.2419C > T (p.Gln807*), which eliminates downstream part of the protein. Another novel mutation is c. (1,053 + 1_1,054-1)_(1,397 + 1_1,398-1)del, which causes deletion of the DNA segment from exon 12 to exon 15.

Two of the other six families are from the same ethnicity and share the same mutation and haplotype patterns, suggesting a founder mutation. Genetic analysis of dysferlinopathy can prevent a wrong diagnosis of myositis for these patients.