DIETARY-FAT CLEARANCE IN NORMAL SUBJECTS IS MODULATED BY GENETIC-VARIATION AT THE APOLIPOPROTEIN-B GENE LOCUS

Apolipoprotein B (apo B) plays a dominant role in cholesterol homeosta sis. Several polymorphic sites within or adjacent to the gene locus fo r apo B have been detected. The X+ allele (XbaI restriction site prese nt) of the XbaI restriction fragment polymorphism on the apo B gene ha s been found in some studies to be associated with higher serum choles terol and/or triglyceride levels and with greater dietary response. Th e present study was designed to evaluate whether the apo B XbaI polymo rphism was associated with the interindividual variability observed du ring postprandial lipemia. Fifty-one healthy young male volunteers [20 X-/X-(X-), and 31 X+/X- or X+/X+ (X+)], homozygotes for the apo E3 al lele, were subjected to a vitamin A-fat load test. Subjects with the X - genotype had significantly greater retinyl palmitate (RP) and apo B- 48 postprandial responses on both the large and the small TRL lipoprot ein fractions compared with X+ subjects. In summary, subjects with the X-/X- genotype at the apo B locus have a greater postprandial respons e than Xi subjects. These differences observed in postprandial lipopro tein metabolism could explain some of the reported associations of thi s polymorphism to coronary heart disease risk.