Counting reactions, not just variants: what malignant hyperthermia can teach precision medicine

Susceptibility to malignant hyperthermia is generally considered to follow an autosomal dominant inheritance pattern with incomplete penetrance. In a recent study in the British Journal of Anaesthesia, Aboelsaod and colleagues integrate national epidemiological data, anaesthetic exposure histories, population genomics, contracture test phenotyping, and Bayesian modelling to estimate the prevalence of individuals capable of developing clinical malignant hyperthermia. Their findings support a threshold model in which variants contribute different degrees of biological liability, potentially modified by other genetic and environmental factors, whereas the probability of reacting during a triggering exposure seems relatively similar once an individual has crossed this threshold. The study also illustrates how combining complementary sources of imperfect evidence can improve risk estimation for rare, exposure-dependent disorders. Ultimately, malignant hyperthermia genetics needs to move beyond categorical variant classification towards variant-specific penetrance estimates that incorporate genetic background, ancestry, exposure history, and other determinants of clinical expression.