HMGCR and juvenile dermatomyositis: Juvenile dermatomyositis (JDM) is the most common IIM in children, with an incidence of 3.2 per million children [3], positivity for anti-HMGCR and anti-SRP54 Ab were present in only 1–2.2 % of pediatric series from the UK and the USA with IIM [1,2,4,5].