Association of a DNA polymorphism in the apolipoprotein C-III gene with diverse hyperlipidaemic phenotypes.

We found an increased prevalence of an Sst-1 restriction fragment length polymorphism (RFLP), localized to the apolipoprotein C-III gene, in lipid clinic patients with diverse hyperlipidaemic phenotypes. Studies on a normolipidaemic control population confirmed previous reports of differing frequencies of the RFLP in different racial groups. Reexamination of the patient data, taking into account racial composition, provided further support for an association of the Sst-1 RFLP with primary hypercholesterolaemia, type III hyperlipoproteinaemia, as well as with hypertriglyceridaemia as had previously been observed. These results suggest that the Sst-1 site is linked to a gene defect with a minor or subtle phenotypic effect which enhances the expression of a co-existent major monogenic defect of lipoprotein transport.