The RNF213 gene, recognized as the predominant susceptibility gene for MMD, encodes an exceptionally large (591 kDa) multidomain protein (mysterin/RNF213) possessing bifunctional enzymatic properties: (i) AAA+ ATPase activity mediating mechanochemical transduction through oligomeric ring formation coupled with putative physical motion, and (ii) E3 ubiquitin ligase activity, mediating substrate ubiquitination for proteasomal degradation or signaling modulation [8]. The gene discussed is APP; the disease is multiminicore myopathy.