Malignant hyperthermia and associated disorders.

Malignant hyperthermia is a pharmacogenetic disorder of skeletal muscle that may cause a life-threatening reaction during administration of general anesthesia. It is inherited in an autosomal dominant pattern and, at least in some families, is caused by a mutation in the ryanodine receptor-calcium-release channel gene on chromosome 19. Malignant hyperthermia displays heterogeneity, making the development of a simple screening test difficult. Malignant hyperthermia may be caused by other biochemical defects affecting intramyoplasmic calcium. Some myopathies, such as central core disease, are frequently associated with malignant hyperthermia susceptibility. In other myopathies, like Duchenne muscular dystrophy, unusual compensatory mechanisms may produce a hypermetabolic state identical to that of malignant hyperthermia.