MH: malignant hyperthermia; MHS: susceptible to malignant hyperthermia; CT: contracture test.
* CT is more definitive than genetic testing, and should be offered. However, because CT requires a surgical muscle biopsy that must be performed at one of only several centers, nearly all patients will choose genetic testing prior to muscle biopsy for CT.
¶ MHS may be inherited as an autosomal dominant trait with up to 50% chance that a family member will be MH positive.
Δ Genetic testing is only approximately 60% sensitive. Patients with negative genetic testing should be offered CT.
◊ Some MHS families carry more than one pathogenic MH variant.