Study of LQT-1213 on QTc-induced Prolongation in Healthy Adult Subjects (Part1) and on Congenital Long QT in Patients Diagnosed With Type 2 or 3 Long QT Syndrome (Part 2).

Part 1: This is a Phase 1b, randomized, double-blind, crossover, dose escalation, placebo-controlled study to evaluate the effect of oral LQT-1213 on dofetilide-induced QTc prolongation in healthy adult subjects. This is a 2-treatment, 2-period crossover study with approximately up to 28 healthy subjects, with screening procedures within 28 days of enrolment. Part 2: This is a Phase 2a, single-blind, placebo run-in, multiple-dose safety study to evaluate the safety, tolerability, and PK of LQT-1213 in patients diagnosed with LQT2 or LQT3. Up to 12 participants with LQT2 and up to 12 participants with LQT3 will be recruited.