MH is considered a dominantly inherited disorder in humans. All closely related members of a family in which MH has occurred must also be considered MH susceptible and managed accordingly, unless proven otherwise. It should be noted that those who have had previous anesthetics without problem cannot be certain they are not at risk; MH related deaths have occurred even though patients have undergone multiple prior uneventful surgeries. Certainly any family with a history of anesthetic deaths or complications should make this known to the anesthesiologist before undergoing surgery. Additionally, they should register their MH susceptibility with the North American MH Registry of MHAUS.