(TTA)n repeat polymorphism in the HMG-CoA reductase gene and cholesterolaemia

Hypercholesterolaemia is one of the main risk factors of atherosclerosis. Both environmental and genetic factors have been implicated in the development of hypercholesterolaemia. The enzyme hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase plays an important role in cholesterol synthesis. Thus we supposed that polymorphisms in this gene could influence cholesterolaemia.

Using PCR, we measured the (TTA)n repeat polymorphism near the Alu sequence of the gene for HMG-CoA reductase in two groups of children selected from opposite ends of the cholesterolaemia distribution curve obtained from measuring cholesterolaemia in 2000 children. Eighty-two children in high- and eighty-six children in low-cholesterolaemic groups participated on the study.

A significant difference was found in the frequencies of the genotypes of the 10+ add alleles (43.9% in high-cholesterolaemic children vs 24.4% in low-cholesterolaemic children p < 0.025). No differences were demonstrated in the frequencies of other genotypes (allele 10+ even and without allele 10). No associations between lipid parameters and genotypes or genotype subgroups within the group of high- and low-cholesterolaemic children were found.

The (TTA)n repeat polymorphism in the gene for HMG-CoA reductase could be another genetic marker that plays a role in the genetic determination of cholesterolaemia.