These include KCNQ1 p.L353L, a synonymous splice site variant and modifier of the LQTS phenotype (5), ANK2 p.S646F, a variant associated with structural heart disease and an adult onset form of LQTS (6), and CPT1A p.P479L, a variant associated with infant death (7, 8) and hypoglycemia (9–11). The gene discussed is KCNQ1; the disease is familial long QT syndrome.