Familial associations of lipids and lipoproteins in families of hypercholesterolemic probands.

We used the Princeton School Family Study hypercholesterolemic recall group to assess whether, and to what degree, the identification of hypercholesterolemic subjects could be improved through the phenomenon of familial lipid and lipoprotein aggregation. A second aim was to assess whether within-family lipid and lipoprotein correlations outlasted the period of shared family environment. Approximately twice as many (as expected) siblings and offspring of hypercholesterolemic probands had plasma total and low density lipoprotein cholesterol levels greater than the 90th and 75th percentiles respectively, emphasizing how identification of hypercholesterolemic subjects can be facilitated by use of the phenomenon of familial aggregation of plasma total and low density lipoprotein cholesterol. After exclusion of the hypercholesterolemic probands from calculations of within-family correlations, and use of natural log transformations for the probands' first-degree relatives' lipids as required, most father/pediatric offspring and mother/pediatric offspring correlations for lipids and lipoprotein cholesterols were significant, while most parent/adult offspring correlations were not significant. All pediatric sibling correlations for lipids and lipoprotein cholesterols were significant; most adult sibling correlations were not significant. The loss of significance and consistency in sibling and parent/offspring lipid and lipoprotein correlations in adults who no longer shared a common household environment points to environmental influences on total, high, and low density lipoprotein cholesterol in kindreds with a hypercholesterolemic proband.