DNA polymorphism at the apolipoprotein B locus is associated with lipoprotein level

A strong association has been uncovered between DNA variation at the apolipoprotein B (apoB) locus (detectable with the restriction endonuclease XbaI) and apoB level. The findings are suggestive of associations also between this DNA polymorphism and total cholesterol as well as fasting triglyceride levels, confirming recent results reported by British workers. The data suggest that lipid/apolipoprotein associations with the XbaI polymorphism are primarily caused by an effect on apoB level. In the present and in a previously reported study we found a strong association between the XbaI polymorphism and the homospecific Ag antigenic variation in low density lipoprotein (LDL) which had previously exhibited associations with lipid levels. The present data indicate that the apoB/lipid associations of the Ag and XbaI polymorphisms may reflect the same phenomenon. The associations reported could reflect variation in an apoB domain close to Ag as well as to the XbaI restriction site that is of importance for lipid binding by apoB. Alternatively, the association of apoB level with the XbaI polymorphism (which reflects a silent third base mutation in a threonine codon) could reflect phenomena related to codon usage.