G-->A substitution at position -75 of the apolipoprotein A-I gene promoter. Evidence against a direct effect on HDL cholesterol levels.

The present study sought to resolve the contradictory evidence as to whether the G-->A substitution at position -75 of the apoA-I gene promoter raises HDL cholesterol (HDL-C) levels by examining the effect of this polymorphism in French Canadians, a relatively genetically homogeneous population. Among 308 women, carriers of the A allele displayed 12% and 10% higher mean plasma HDL-C and apoA-I concentrations, respectively, than did noncarriers. Among 345 men, no effect of the A allele was noted.

Prevalence of alleles encoding defective lipoprotein lipase in hypertriglyceridemic patients of French Canadian descent.

It has previously been estimated that due to genetic "founder effects," 97% of lipoprotein lipase (LPL) gene alleles conferring type I hyperlipoproteinemia (HLP) in French Canadians encode one of the following mutant LPL forms: Gly188-->Glu, Pro207-->Leu, or Asp250-->Asn. Although the genetic basis of type I HLP is known to be homozygosity for LPL deficiency, that for other forms of HLP, especially types IV, and V HLP, is not clear. It is also unclear whether hypertriglyceridemia due to very low density lipoprotein (VLDL) overproduction can be distinguished phenotypically from that due to defective catabolism of plasma lipoprotein triglycerides.