RYR1 and centronuclear myopathy: Comparable to the Smyd1 CKO, some individuals with CNM caused by RYR1 mutations exhibit regional myofibrillar disorganization and hypotrophy (Bevilacqua et al., 2011), but, unlike the Smyd1 CKO, type I fiber predominance is common (Wilmshurst et al., 2010).