The study, which began in 1991, focuses on genes that influence the lipoprotein profile in members of randomly ascertained Mexican-American families, with particular emphasis on genetic effects on reverse cholesterol transport. An overall objective is to investigate the pleiotropic effects of these "lipoprotein genes" and their interactions with genes that affect non-insulin dependent diabetes mellitus (NIDDM) antecedents and body fat distribution. The interactions of lipoprotein genes with sex hormonal status and with environmental risk factors such as diet, exercise, and smoking are investigated. Genetic effects on standard lipoprotein variables are examined, e.g. plasma concentrations of lipoproteins and apolipoproteins. Several novel lipoprotein phenotypes also are analyzed, e.g. amounts of esterified and unesterified cholesterol and of specific apolipoproteins in lipoprotein subclasses. Molecular, biochemical, and statistical genetic approaches are used to detect, localize and characterize genes that influence quantitative phenotypes associated with lipoproteins, NIDDM, and obesity, and to quantify the effects of known candidate loci on these phenotypes.