RNF213 and multiminicore myopathy: Recently, the p.R4810K (c.14429G>A: rs112735431) variant of the ring finger 213 gene (RNF213) was identified as an MMD susceptibility variant by two independent groups in Japan.[16,17] Furthermore, one of these groups cloned the entire RNF213 cDNA, characterized the functions of RNF213 as ATPase and E3 ligase, and showed a founder effect of this variant among East Asian patients.