Figure 1. The time to onset of ryanodine contractures in participants diagnosed by halothane and caffeine testing. The diagnoses were determined by (A) the North American Malignant Hyperthermia Group protocol using the recommended threshold for genetic studies (0.7-g contracture to 3% halothane or >or= to 0.2-g contracture to 2 mM caffeine)[3]or (B) the European Malignant Hyperthermia Group protocol and the time to onset of contracture to 1 [micro sign]M ryanodine was recorded. A line is drawn at 12 min to indicate the best separation of the malignant hyperthermia-susceptible and malignant hyperthermia-negative participants.