Recent studies demonstrate that specific RYR mutations confer sex– and gene–dose-dependent susceptibility to pharmacological (halogenated anesthetic) and environmental (heat) stressors that trigger malignant hyperthermia and muscle damage in otherwise asymptomatic individuals (Barrientos et al. 2012; Yuen et al. 2012). The gene discussed is RYR2; the disease is Malignant hyperthermia.