Figure 1. (A) Receiver operating characteristic (ROC) curve for 3% halothane based on 118 controls and 30 D6 cases. (B) The ROC curve for 2 mM caffeine based on 119 controls and 32 D6 cases. (C) The ROC curve for two-component caffeine-halothane contracture test (3% halothane, 0.3 g 2 mM caffeine) based on 117 controls and 32 D6 cases. Circled values on the ROC curves are the cutpoints chosen using the maximal Youden index.