Results of in vitro contracture tests for the diagnosis of malignant hyperthermia susceptibility in monozygote twins.

Abstract

Malignant hyperthermia susceptibility is a pharmacogenetic disorder in which susceptible individuals may develop a potentially life-threatening hypermetabolism when exposed to certain anaesthetic agents. The most common diagnostic method is the in vitro contracture test (IVCT) of skeletal muscle biopsies. There is a wide variation in the size of contractures between susceptible individuals and the reproducibility of the test in humans has not been evaluated. We have performed the IVCT in 4 monozygote pairs of twins, which gave us on opportunity to study the reproducibility. The clinical diagnoses were consistent in all twin pairs, although slight differences in contractures and thresholds were seen. In this material the reproducibility of the IVCT was found to be satisfactory.