ASSOCIATION OF APOLIPOPROTEIN(A) PHENOTYPES IN CHILDREN WITH FAMILY HISTORY OF PREMATURE CORONARY-ARTERY DISEASE

Although blacks have higher plasma levels of lipoprotein(a) [Lp(a)] th an whites, the Lp(a) levels are not associated with clinical coronary artery disease (CAD) or parental history of myocardial infarction in b lacks. To explore whether ethnic differences in the pathogenicity of L p(a) are related to the thrombogenic component of Lp(a), this study in vestigated in children the associations of apolipoprotein(a) [apo(a)] phenotypes and Lp(a) levels with family history of premature CAD. Subj ects were 46 children aged 7 to 11 years divided according to family h istory of premature CAD and assessed for Lp(a), apo(a) phenotypes, and other lipids and lipoproteins. The prevalence of small isoforms was h igher in children with positive family history of premature CAD than i n children with negative family history of premature CAD (32% versus 1 0%). Large isoforms were more prevalent in whites (24% versus 6%), and medium-sized isoforms were more prevalent in blacks (75% versus 52%). The black/white difference was smaller (19% versus 24%) in regard to small isoforms. Lp(a) levels were inversely related to apo(a) size in both blacks and whites (P = .084 and P = .049, respectively). Single-b anded small apo(a) isoforms predicted positive family history of prema ture CAD, independent of ethnicity and Lp(a) levels. Small apo(a) isof orms in children were independent predictors of family history of prem ature CAD. Unlike Lp(a), they appear to be equally pathogenic for blac ks and whites.