Variation at the apo AI/CIII/AIV gene complex is associated with elevated plasma levels of apo CIII

A number of studies have reported that a variant allele (S2) of the apo AI/CIII/AIV complex is associated with high plasma lipid levels in some populations and furthermore that the frequency of this allele is 2-5-fold higher in patient groups with premature coronary heart disease compared to control groups. This study shows in the healthy "English" population that the S2 allele is associated with elevated plasma apo CIII levels but not with low apo AI levels. In addition, it shows that the allele is associated with elevated plasma levels of apo B in men. Regression analysis shows in both men and women that apo CIII levels are positively correlated with plasma triglyceride levels and moreover that they are a stronger predictor of this parameter than apo AI, B or AIV. Apo CIII levels are also an independent predictor of total plasma cholesterol and HDL-cholesterol levels in males and females, respectively. Together these data suggest that a genetic predisposition to develop elevated plasma levels of apo CIII, alone or in combination with elevated plasma apo AIV levels, is the primary defect responsible for the association of the S2 allele with hyperlipidemia and/or premature CHD.