To determine prospectively the role of elevated plasma triglyceride (TG) as a risk factor for 20-year coronary heart disease (CHD) mortality in familial combined hyperlipidemia (FCHL) and familial hypertriglyceridemia (FHTG), the familial forms of hypertriglyceridemia. Also, to perform genetic epidemiologic studies of recently identified lipoprotein risk factors for CHD, including Atherogenic Lipoprotein Phenotypes (ALP) based on subclasses of low-density lipoproteins (LDL), Lipoprotein(a) (Lp(a)) and apolipoprotein (apo) B plasma levels, and apo E isoforms.