In support of this hypothesis, a functional study of a mutation causing malignant hyperthermia susceptibility (R174W) in S4 of VSD I of Cav1.1 revealed that this mutation reduces Cav1.1 ionic current, but does not affect Cav1.1-dependent SR Ca2+ release [170] (Fig. 12). The gene discussed is CACNA1S; the disease is Malignant hyperthermia.