Interrelationships between low density lipoprotein receptor defect, serum fatty acid composition, and serum cholesterol concentration

It is known that, in the general human population, serum fatty acid composition is correlated with serum triacylglycerol and cholesterol concentrations. The goal of the present study was to analyze whether the same is true of individuals who have a low density lipoprotein receptor (LDL-R) defect. Concentrations of 16 different fatty acids, cholesterol, triacylglycerol, and major lipoproteins in serum were determined in eight individuals who had (FH-North Karelia), the most common LDL-R defect in Finland, which causes familial hypercholesterolemia, and in their 30 relatives belonging to a single large pedigree as controls. The average number of double bonds (i.e., degree of desaturation) in serum fatty acids correlated negatively with the concentrations of serum total cholesterol (r = 0.27, P < 0.05) and total triacylglycerol (r = -0.71, P < 0.001) and positively with the number of fish meals per week (r = 0.50, P < 0.01), which was analyzed in all pedigree members jointly. These effects were similar in individuals having LDL-R defect, in which group the correlation coefficients were -0.31 (P = NS), -0.99 (P < 0.001), and 0.79 (P = NS) for serum total cholesterol, triacylglycerol, and weekly fish meals, respectively. Thus, LDL-R defect does not impair the correlation between serum fatty acid composition and serum triacylglycerol concentration. This result is in agreement with dietary studies that have shown that familial hypercholesterolemia patients respond very favorably to dietary therapy.