Background: Apolipoprotein A5 (APOA5) plays an important role in plasma triacylglycerol (TG) homeostasis. Five polymorphisms (1131T>C, c.-3A>G, c.56C>G, IVS3+476G>A, and c.1259T>C) in the APOA5 gene define three common haplotypes (APOA5*1, APOA5*2, and APOA5*3) in Caucasian individuals. Our aim was to determine whether these haplotypes could modulate the postprandial response in young healthy males.
Design and methods: Eighty-eight APO E3/3 volunteers [67 with (-1131T and 56C) APOA5*1 haplotype, 12 with (-1131C and 56C) APOA5*2 haplotype, and nine with (-1131T and 56G) APOA5*3 haplotype] underwent a fat load test consisting of the consumption of 1 g of fat per kilogram body weight and 60,000 IU vitamin A. Blood samples were taken at time 0, at every hour until the sixth hour, and at every 2.5 h until the 11th hour. Total plasma cholesterol (C) and TG, and C, TG, apolipoprotein B-100, apolipoprotein B-48, and retinyl palmitate in lipoprotein fractions were determined.
Results: Subjects with the APOA5*2 and APOA5*3 haplotypes had a higher area under the curve of total plasma TG (P = 0.03), large TG-rich lipoprotein (TRL)-TG (P = 0.02), small TRL-TG (P = 0.04), small TRL-C (P = 0.04), large TRL-C (P = 0.03), and small apolipoprotein B100 (P = 0.04) than subjects with the APOA5*1 haplotype.
Conclusions: Our findings show that the presence of the APOA5*2 and APOA5*3 haplotypes in the APOA5 gene is associated with a higher postprandial response that could be involved in the higher risk of coronary heart disease associated with the 56G and -1131C alleles.