RYR1 and rhabdomyolysis: MH-associated RYR1 mutations have also been implicated in some forms of rhabdomyolysis/exercise induced/heat intolerance,1,6,7 King Denborough syndrome a myopathic syndrome characterized by skeletal abnormalities, dysmorphic features and MH susceptibility,8 as well as some forms of periodic paralysis.9 These results highlight the fact that patients with mutations in one gene may present with a variety of different phenotypes.