Association of Apolipoprotein A Phenotypes and Oxidized Low-Density Lipoprotein Immune Complexes in Children

Background Small apolipoprotein A (apo[A]) phenotypes and oxidized low-density lipoprotein immune complexes (oxLDL-ICs) are known to be associated with the development of atherosclerosis in adults. Presence of these factors in children and their relationships with other known cardiovascular risk factors have not been well documented. Objective To examine the relationship of oxLDL-ICs with apo(A) phenotypes and other known cardiovascular risk factors in children. Design A survey of asymptomatic 9- to 11-year-old children, randomly selected from a cohort of children stratified based on family history of premature coronary artery disease. Setting A preventive medicine research institute. Participants Thirty-five children with or without a family history of premature coronary artery disease who are participating in a longitudinal cardiovascular health study. Main Outcome Measures The influence of apo(A) phenotypes on plasma levels of oxLDL-ICs after controlling for lipid/lipoprotein levels, percentage of body fat, and physical fitness. Results Oxidized low-density lipoprotein immune complexes were significantly correlated with the levels of total cholesterol ( r = 0.56, P ≤.05), low-density lipoprotein cholesterol ( r = 0.64, P ≤.01), and low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ( r = 0.54, P r = 0.49, P ≤.06) and percentage of body fat ( r = 0.48, P ≤.06). However, they achieved only a borderline level of statistical significance after adjustment for multiple comparisons. Multiple regression analysis demonstrated that small apo(A) phenotypes, levels of low-density lipoprotein cholesterol, and family history of premature coronary artery disease explained 54% of the variation of oxLDL-ICs using a parsimonious model ( P =.001). Conclusions Significant correlations exist between oxLDL-ICs and known cardiovascular risk factors in children. The association of oxLDL-ICs with the genetically controlled small apo(A) phenotype suggests that the genetic predisposition to immune complex formation may be an important determinant of future coronary artery disease.