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). Here, RYR1 is linked to congenital fiber-type disproportion myopathy.