As many as 450,000 Americans die every year from a sudden, fatal heart condition, and in slightly more than one in ten cases the cause remains unexplained even after an autopsy. Researchers from the University of Maryland School of Medicine (UMSOM) and their colleagues found that nearly 20 percent of patients with unexplained sudden cardiac death—most of whom were under age 50—carried rare genetic variants. These variants likely raised their risk of sudden cardiac death. In some cases, their deaths may have been prevented if their doctors had known about their genetic predisposition to heart disease. The study findings were published last week in JAMA Cardiology.