Sudden death is a major problem in industrially developed countries. Despite a decline in ischemic heart disease mortality and the progress has been made in resuscitation, treatment of sudden death victims is frequently unsuccessful. the ideal solution would be to prevent the disease process that causes the initial episode of cardiac arrest. Parental sudden death is an independent risk factor for sudden death. So, detect a gene predisposing to sudden death may help provide better identification of subjects at high risk of cardiac arrest. This research is a genetic study of sudden cardiac death, recruited 2000 subjects in out-of-hospital cardiac arrest.