Frequency and effect of human apolipoprotein A-IV polymorphism on lipid and lipoprotein levels in an Icelandic population.

Human apolipoprotein A-IV (apo A-IV) exhibits a genetic polymorphism with two common alleles, A-IV1 and A-IV2, in Caucasian populations. We have investigated this polymorphism in the Icelandic population. The frequencies of the two alleles are significantly different from middel European populations with a higher frequency of the A-IV2 allele (0.117 versus 0.077) occurring in Iceland. The alleles at the apo A-IV locus have significant effects on plasma high density lipoprotein cholesterol (HDL-C) and triglyceride levels. The average effect of the A-IV2 allele is to raise HDL-C by 4.9 mg/dl and to lower triglyceride levels by 19.4 mg/dl. We estimate that the genetic variability at the apo A-IV gene locus accounts for 3.1% of the total variability of HDL-C and for 2.8% of the total variability of triglycerides in the population from Iceland. This confirms and extends our previous observations on apo A-IV allele effects in Tyroleans in an independent population.