Malignant hyperthermia

While malignant hyperthermia itself is not inherited, malignant hyperthermia susceptibility (MHS) is inherited in an autosomal dominant manner. This means that having a mutation in only one copy of the responsible gene is enough to make someone susceptible to having malignant hyperthermia.

Most people diagnosed with malignant hyperthermia or MHS have a parent with MHS; however, the parent may not have experienced an episode of malignant hyperthermia. Therefore, the family history may appear to be negative when other family members are susceptible. In some cases, a person with MHS is affected due to having a new (de novo) mutation that was not inherited from a parent. Parents of a person with an apparently new mutation may be evaluated by having contracture testing (a muscle biopsy to determine susceptibility) or molecular genetic testing, if the mutation in the affected person is known.

Each child of a person with MHS has a 50% (1 in 2) risk to inherit MHS.

The risks to siblings of an affected person depend on whether the affected person has a new mutation or inherited MHS from a parent. If a parent has MHS, each sibling as a 50% (1 in 2) risk to have MHS. When both parents appear unaffected based on evaluation, the risk to siblings of an affected person appears to be low.

The risk to other family members of an affected person also depend on whether an affected person's parent has the condition. If a parent also has MHS, other family members are at risk.^[1]

People interested in learning about specific genetic risks to themselves or family members should speak with a genetics professional.

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.