Reduction in RYR1 protein content, due to compound heterozygous mutations, has been reported in several RYR1-related myopathies including CCD, multiminicore disease (MmD), centronuclear myopathy (CNM), congenital fiber type disproportion (CFTD), dusty core disease (DuCD), and core rod myopathy (CRM; Ogasawara and Nishino, 2021). The gene discussed is RYR1; the disease is centronuclear myopathy.