This gene encodes the ryanodine receptor 1 calcium-release channel (RyR1) of the sarcoplasmic reticulum and mutations therein have been identified in ∼30% of all CM patients.2,5 Interestingly, mutations in RYR1 are linked to various disease phenotypes, including those with dominantly inherited central core disease (CCD, MIM#11700) and mainly recessively inherited subgroups of multiminicore disease (MmD, MIM#255320), centronuclear myopathy (CNM) and congenital fibre type disproportion. Here, RYR1 is linked to cutaneous mastocytosis.