Inheritance and Penetrance of Malignant Hyperthermia

No longer can the inheritance of human MH be considered solely autosomal dominant with variable penetrance, because more than one genetic locus has been identified in some families. Six nonconsanguineous families harbor at least two genes causing MH.^[30] MHS homozygotes are common in affected pigs but rare in human populations. MHS homozygous humans appear clinically normal but exhibit stronger responses to IVCT and CHCT than do heterozygous individuals. ^[31] They do not exhibit signs or symptoms of CCD.