Diagnostic re-labelling of myopathy subtype after anti-HMGCR testing was more common in the statin-naïve group (5/8 [prior diagnoses: polymyositis (2), dermatomyositis, limb-girdle muscular dystrophy, tropical infection] vs 16/101 [prior diagnoses: other IIM subtype (11), myofibrillar myopathy (2), rhabdomyolysis (2), autoimmune hepatitis (1)], P = 0.007). This evidence concerns the gene HMGCR and dermatomyositis.