IFIH1 and dermatomyositis: Anti-MDA5 Ab-positive DM patients frequently develop RPILD, especially in East Asia.[10] Reports of anti-MDA5 Ab-positive DM patients in Japan demonstrated the following prevalence: CADM, 85% (CDM, 15%); ILD, 92%; RPILD, 54%; and mortality, 46%,[11] indicating that anti-MDA5 Ab-positive DM patients have poor prognoses.