We perform whole-exome sequencing on 31 sporadic MMD subjects and 10 healthy volunteers, and identify 12 predisposing mutations of seven genes (RNF213, CCER2, HLA-DRB1, NSD-1, PDGFRB, PHACTR1 and POGLUT1) associated with MMD and SNV (c.13185159G>T, p.V265L) on PHACTR1 associated with its progression. The gene discussed is PHACTR1; the disease is multiminicore myopathy.