Detection of a novel RYR1 mutation in four malignant hyperthermia pedigrees

Malignant hyperthermia (MH) is a potentially fatal autosomal dominant disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anaesthetics and depolarizing muscle relaxants. To date, six mutations in the skeletal muscle ryanodine receptor gene (RYR1) have been identified in malignant hyperthermia susceptible (MHS) and central core disease (CCD) cases. Using SSCP analysis, we have screened the RYR1 gene in affected individuals for novel MHS mutations and have identified a G to A transition mutation which results in the replacement of a conserved Gly at position 2433 with an Arg. The Gly2433Arg mutation was present in four of 104 unrelated MHS individuals investigated and was not detected in a normal population sample. This mutation is adjacent to the previously identified Arg2434His mutation reported in a CCD/MH family and indicates that there may be a second region in the RYR1 gene where MHS/CCD mutations cluster.