We selected LQT-5 mutations, KCNE1-L51H (Bianchi et al., 1999) and KCNE1-G52R (Ma et al., 2003), that inhibit IKS channel activity via alteration of KCNE1/KCNQ1 interactions (Bianchi et al., 2000). The gene discussed is KCNE1; the disease is long QT syndrome 5.