RYR2 and familial long QT syndrome: In total, 5 of the 105 (5%) identified mutations had occurred de novo in the index patient (four LQTS mutations and one CPVT mutation, KCNQ1 p.T169R, KCNH2 p.E95G, KCNH2 p.Q61R, SCN5A p.V411M, and RYR2 p.S2246L, see Table 2).