RYR1 and centronuclear myopathy: Both dominant and recessive mutations have been reported in RYR1. Dominant mutations have traditionally been associated with central core disease (CCD) and/or a susceptibility to malignant hyperthermia (MHS) [2], while recessive mutations predominate in patients with multiminicore disease (MmD), centronuclear myopathy (CNM), and congenital fiber type disproportion (CFTD) [4-6].