Genetic analysis of the Stanford LRC family study data. II. Structured exploratory data analysis of lipids and lipoproteins

A newly developed methodology for the assessment of mode of inheritance of continuously distributed traits in nuclear families, structured exploratory data analysis (SEDA), is applied to lipid and lipoprotein measurements. Specifically, three measures: the major gene index (MGI), the pairwise midparental correlation coefficient (MPCC), and the offspring between parents (OBP) curves are used to determine whether these trait expressions are more major gene, sporadic, or multifactorial relative to one another. Triglycerides and the closely-related VLDL-cholesterol measurement appears to be transmitted through some major components. HDL-cholesterol measurements are more consistent with some degree of multifactorial transmission or a major gene model with additive allelic effects and similar allele frequencies. The results for LDL-cholesterol suggest a modicum of major gene influences. The composite total cholesterol measurement appears to be under multifactorial transmission but of lower order than height. Younger families who were selected through a parent with high lipid levels exhibit some major gene influences which do not appear in the older families. Several possible explanations are proposed for this difference.