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Molecular genetic linkage studies on the inherited human disorder malignant hyperthermia have resulted in the mapping of the locus for malignant hyperthermia susceptibility (MHS) to the twenty centimorgan genetic interval in the q12-13.2 region of chromosome 19 defined by the anonymous polymorphic DNA markers D19S9 and BCL3. The mapping of the MHS locus to this interval now allows diagnosis of MHS in selected families with an accuracy of 97.5% using closely linked polymorphic DNA markers.

The muscle disease malignant hyperthermia is a disorder of intracellular free Ca2+ regulation in both humans and pigs. Current evidence indicates that the Ca2+ channel of the sarcoplasmic reticulum of MH muscle is abnormally sensitive to Ca2+ and to halothane. Mitochondria, the sarcolemma and the transverse tubule appear not to be involved in primary pathogenesis of MH. Molecular genetic studies indicate that the MH gene is on human chromosome 19 and that the likely candidate gene is that coding for the Ca2+ channel.