Significant associations between lipoprotein(a) and corrected apolipoprotein B-100 levels in African–Americans

Abstract

ObjectivesLipoprotein(a), Lp(a), represents an apolipoprotein (apo) B-carrying lipoprotein, yet the relationship between Lp(a) and apoB levels has not been fully explored. MethodsWe addressed the relationship between Lp(a) and apoB-containing lipoprotein levels in 336 Caucasians and 224 African–Americans. Our approach takes unique molecular properties of Lp(a) as well as contribution of Lp(a) to the levels of these lipoproteins into account. ResultsLevels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), apoB and apoB/apoA-1 did not differ across ethnicity. African–Americans had higher levels of Lp(a) and high-density lipoprotein cholesterol and lower triglyceride levels compared to Caucasians. Lp(a) levels were correlated with levels of TC (p < 0.005), LDL-C (p < 0.001), apoB (p < 0.05) or apoB/apoA-1 (p < 0.05) in both ethnic groups. These associations remained significant only in African–Americans after adjustments for the contribution of Lp(a)-cholesterol or Lp(a)-apoB. Furthermore, taking Lp(a)-apoB into account, allele-specific apo(a) levels were significantly associated with apoB levels and the apoB/apoA-1 ratio in African–Americans. The latter associations in African–Americans remained significant for allele-specific apo(a) levels for smaller apo(a) sizes (<26 K4 repeats), after controlling for the effects of age, sex, and BMI. ConclusionsAlthough TC, LDL-C, and apoB levels were comparable between African–Americans and Caucasians, the associations of these parameters with Lp(a) and allele specific apo(a) levels differed between these two ethnic groups. In African–Americans, apoB and apoB/apoA-1 remained consistently and positively associated with both Lp(a) and allele-specific apo(a) levels after adjustments for the contribution of Lp(a)-apoB. The findings suggest an interethnic difference with a closer relationship between Lp(a) and apoB among African–Americans.