No abstract

Based on genetic and diagnostic test data, more than one MHS allele associated with the MHS phenotype was evidenced in four families. These data should be considered in view of the use of genetics for the diagnosis of MHS and when reaching conclusions of genetic heterogeneity in MHS families. Taking into account the usual dominant mode of transmission of MHS and the size of the investigated population, the authors propose an evaluation of the incidence of the MHS in the general population based on genetic data.

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. To date, the ryanodine receptor gene (RYR1) has been shown to be mutated in a small number of malignant hyperthermia susceptible (MHS) cases. To determine if a common RYR1 mutation exists that might account for a significant number of MHS cases, we have investigated the RYR1 gene in unrelated patients for the presence of new mutations by the single-stranded conformation polymorphism method and have identified a novel Gly341Arg mutation which accounts for approximately 10% of Caucasian MHS cases. The implications of this common mutation in MHS diagnosis and heterogeneity studies are discussed.

The proband in this kindred is the first reported homozygote to have presented with an MH episode. The homozygotes in this pedigree do not have an overt myopathy. The sensitivity of muscle samples to caffeine clearly distinguished the two homozygotes from other heterozygous-susceptible individuals. No clear differentiation was observed with the halothane contracture results.

Objective: The aim was to determine whether myofilament Ca 2q sensitivity is altered in skinned cardiac fibres from endotoxin-treated Ž .