KCNJ2 and catecholaminergic polymorphic ventricular tachycardia: CPVT has been classified by gene mutation into five subtypes: CPVT1 (involving the RyR2 gene) and CPVT3 (TRDN [triadin]) present with symptoms at around 10 years of age; CPVT2 (involving the CASQ2 gene) manifests symptoms at around seven years of age, while CPVT4 (involving the ankyrin-2 gene [ANK2]) and CPVT5 (involving the potassium inwardly-rectifying channel subfamily J member-2 gene [KCNJ2]) presents with symptoms at four and 2.5 years of age.