Sudden cardiac death (SCD) is one of the most common causes of death in 
developed countries, with most SCDs involving the elderly, and structural heart 
disease evident at autopsy. Each year, however, thousands of sudden deaths 
involving individuals younger than 35 years of age remain unexplained after a 
comprehensive medicolegal investigation that includes an autopsy. In fact, 
several epidemiologic studies have estimated that at least 3% and up to 53% of 
sudden deaths involving previously healthy children, adolescents, and young 
adults show no morphologic abnormalities identifiable at autopsy. Cardiac 
channelopathies associated with structurally normal hearts such as long QT 
syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), 
and Brugada syndrome (BrS) yield no evidence to be found at autopsy, leaving 
coroners, medical examiners, and forensic pathologists only to speculate that a 
lethal arrhythmia might lie at the heart of a sudden unexplained death (SUD). In 
cases of autopsy-negative SUD, continued investigation through either a 
cardiologic and genetic evaluation of first- or second-degree relatives or a 
molecular autopsy may elucidate the underlying mechanism contributing to the 
sudden death and allow for identification of living family members with the 
pathogenic substrate that renders them vulnerable, with an increased risk for 
cardiac events including syncope, cardiac arrest, and sudden death.