RYR1 and rhabdomyolysis: We next examined the levels of a subset of skeletal muscle transcription factors, including NFAT and MEF2 family members,40–42 and of muscleblind (MBNL1).43 The transcript expression levels in muscles from disease controls, i.e. patients with RYR1-related rhabdomyolysis/exercise intolerance were similar to those found in muscles from controls (Fig. 4B).