Association between lipoprotein(a) levels, apo(a) isoforms and family history of premature CAD in young Asian Indians

Objectives: The purpose of this study was to explore the association between lipoprotein (a) [Lp(a)] levels, apo(a) isoforms and family history of premature coronary artery disease (CAD) in young Asian Indians. Design and methods: 220 patients (age <40 years) with angiographic evidence of CAD and 160 age matched healthy controls were enrolled for the study. Thirty one percent of the patients and 17% of the controls had positive family history (PFH) of premature CAD. Plasma Lp(a) levels were determined by ELISA and apo(a) isoform size was determined using high-resolution immunoblotting method. Results: Median plasma Lp(a) levels were 2.5 times higher in patients as compared to controls (30 mg/dL vs 12.7 mg/dL; p<0.05). The patient group having a heterozygous apo(a) isoform pattern showed higher Lp(a) levels as compared to the homozygous group (44.0 +/- 38.7 vs 28.0 +/- 26.4 mg/dL;p<0.001). Further low molecular weight apo(a) isoforms (LMW; <22 KIV repeats) were prevalent among CAD patients with PFH as compared to negative family history (62% vs 14%,p<0.05) and this group had the highest Lp(a) levels. Stepwise regression analysis showed that Lp(a) levels and not the apo(a) isoform size, entered the model as significant independent predictors of CAD in young Asian Indians. Conclusions: This study suggests that elevated Lp(a) levels confer genetic predisposition to CAD in young Asian Indians. Thus determination of Lp(a) levels along with other risk factors should be used to assess overall risk for CAD in this ethnic group. (c) 2008 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.