sentence: However , in younger populations , SCD is usually caused by genetic diseases such as inherited arrhythmogenic cardiomyopathies including hypertrophic cardiomyopathy ( HCMP ) , dilated cardiomyopathy ( DCMP ) and arrhythmogenic right ventricular cardiomyopathy ( ARVC ) , and inherited cardiac ion channel diseases including Brugada syndrome ( BrS ) , congenital long QT syndrome ( LQTS ) , short QT syndrome ( SQTS ) , catecholaminergic polymorphic ventricular tachycardia ( CPVT ) and idiopathic ventricular fibrillation or tachycardia ( IVF / IVT ) .