The association of serum lipoprotein(a) levels, apolipoprotein(a) size and (TTTTA) n polymorphism with coronary heart disease

Abstract

Background: The association between lipoprotein(a) levels, apolipoprotein(a) size and the (TTTTA) n polymorphism which is located in the 5′ non-coding region of the apo(a) gene was studied in 263 patients with severe coronary heart disease and 97 healthy subjects. Methods: Lp(a) levels were measured by ELISA, apo(a) isoform size was determined by SDS–agarose gel electrophoresis, and analysis of the (TTTTA) n was carried out by PCR. For statistical calculation, both groups were divided into low (at least one apo(a) isoform with ≤22 Kringle IV) and high (both isoforms with >22 KIV) apo(a) isoform sizes, and into low number (<10 in both alleles) and high number of (≥10 at least one allele) TTTTA repeats. Results: Lp(a) levels were higher ( P=0.007), apo(a) isoforms size ≤22 KIV and TTTTA repeats ≥10 were more frequent ( P=0.007 and 0.01) in cases than in controls. Lp(a) levels were found to be increased with low apo(a) weight in both groups (both P<0.0001). In multivariate logistic regression analysis, only the Lp(a) levels ( P=0.005) and (TTTTA) n polymorphism ( P=0.002) were found to be significantly associated with CHD. Conclusion: Nevertheless, these results indicate that in CHD patients the (TTTTA) n polymorphism has an effect on Lp(a) levels which is independent of the apo(a) size.