Interaction of two lipid disorders in a large French-Canadian kindred.

This study investigates the pedigree of 508 individuals over five generations identified by an individual with hypertriglyceridemia, familial hypercholesterolemia, and a IIb lipoprotein electrophoretic phenotype. The sample of 378 living individuals studied extensively for risk factors and disease status was distributed among maternal (170) and paternal (176) relatives and the codescendants (32) of the index case. It was found that the distributions of the plasma lipid and lipoprotein abnormalities in the different subsets of the kindred were consistent with the presence of two separate hereditary lipid disorders: familial hypercholesterolemia on the paternal side and familial hyperprebetalipoproteinemia on the maternal side. This combination of disorders with a possible contribution from factors influencing glucose metabolism was associated with high frequency of hypercholesterolemia and its clinical manifestations and of cardiovascular morbidity among the codescendants. An interaction effect is suggested as an explanation for the unusually high prevalence of hyperlipidemia among the codescendants and for the presence of a IIb phenotype in the index case.