INA and Romano-Ward syndrome: •   Associated with mutations in atleast 15 genes   •   Three main genes:KCNQ1(LQTS1),KNCH2 (LQTS2), andSCN5A (LQTS3) (75% of cases)   •   IKr (LQTS1),IKs (LQTS2),INa(LQTS3),IK1 (LQTS7), andICa-L(LQTS8)   •   AD LQTS with QT prolongationalone (Romano-Ward syndrome)LQTS 1–6   •   AD LQTS7 (Anderson-Tawilsyndrome): facial dysmorphismand hyper/hypokalemic periodicparalysis   •   AD LQTS8 (Timothysyndrome) prolonged QT,facial dysmorphism, cardiacmalformations, and autism   •   Autosomal recessive LQTS(Jervell and Lange-Nielsonsyndrome) extremely prolongedQT interval with congenitaldeafness