There has been dramatic improvement in our understanding of what causes MH and who is at risk. Over 80 genetic defects have been associated with MH. MH susceptibility is inherited with an autosomal dominant inheritance pattern. This means that children and siblings of a patient with MH susceptibility usually have a 50% chance of inheriting a gene defect for MH, and hence would also be MH susceptible. They, therefore, may develop an MH reaction upon exposure to triggers.
Nevertheless, those who are carriers for susceptibility may be completely unaware of this risk unless they or a family member developed a life-threatening crisis during anesthesia. It is important to know that not everyone who has a gene defect linked to MH develops the MH crisis upon each exposure to the triggering anesthetics.