Identification of a novel mutation and genotype-phenotype relationship in MEGF10 myopathy

Mutations in MEGF10 are associated with early-onset myopathy, areflexia, respiratory distress, and dysphagia (EMARDD). Recently, a mild variant phenotype of EMARDD has been reported in patients with multiple minicores in the myofibers. However, some reported patients had no clear cores. We present a patient who had progressive weakness since his 30 s and then developed severe respiratory failure at the age of 66 years and found that he had a novel mutation, p.G739R, in MEGF10. He had no clear core in the biopsied muscle. We summarize the clinical and genetic characteristics of the current and reported patients with MEGF10 and statistically evaluate the genotype-phenotype correlation. Results show that patients with missense mutations in at least one allele had significantly later onset than those with biallelic truncation mutations.