Japanese multiple epidermal growth factor 10 (MEGF10) myopathy with novel mutations: A phenotype-genotype correlation.

Mutations in the multiple epidermal growth factor-like domains 10 (MEGF10: NM_032446.2) gene are known to cause early-onset myopathy characterized by areflexia, respiratory distress, and dysphagia (EMARDD: OMIM 614399), and a milder phenotype of minicore myopathy. To date, there have been reports of six families with EMARDD and one with a milder disorder. Cysteine mutations in the extracellular EGF-like domain may be responsible for the milder phenotype, but the relationship is not conclusive because of the few reports of this disorder. We here present two Japanese patients with MEGF10 mutations: one with EMARDD phenotype who had a novel homozygous frameshift mutation, c.131_132del, and the other with the milder phenotype who harbored a compound heterozygous mutation, c.2981-2A > G, and a novel missense mutation, p.Cys810Tyr. This is the first report on East Asian patients with MEGF10 myopathy showing two phenotypes, indicating the genotype-phenotype correlation in MEGF10 myopathy.