CALM1 and polymorphic ventricular tachycardia: More specifically, this de novo missense mutation c.A314>C in exon 5 of the CALM1 gene was identified in a seemingly healthy 6-year-old boy, with no family history of cardiac disease, who exhibited profound QT prolongation with an increasing heart rate before the recurrence of polymorphic ventricular tachycardia at a pediatric intensive care unit [27].