Low levels of 'good' cholesterol don't increase heart disease risk

Washington, June 4 : Lower levels of high-density lipoprotein (HDL) cholesterol or 'good' cholesterol due to a gene mutation don't increase ischemic heart disease risk, according to a new study.

Various studies have revealed that a low plasma level of HDL cholesterol is associated with an increased risk of ischemic heart disease (IHD).

However, whether HDL cholesterol is a primary factor in the development of IHD is not clear, in part because of other factors related to low HDL cholesterol levels, such as plasma triglycerides, which may contribute independently to increases in cardiovascular events.

"... studies of genetic disorders that lower HDL cholesterol without increases in plasma triglycerides and remnant lipoproteins provide an ideal system in which to assess the consequences of isolated, lifelong low HDL cholesterol levels," write authors.

The team led by Dr Ruth Frikke-Schmidt, Ph.D., of the University of Copenhagen, Denmark examined whether mutations in the gene ABCA1, which genetically reduce HDL cholesterol levels but do not increase plasma triglyceride levels, are associated with an increased risk of IHD.

The researchers used three studies, Copenhagen City Heart Study (CCHS), the Copenhagen General Population Study (CGPS), and the Copenhagen Ischemic Heart Disease Study.

They analysed data on HDL cholesterol levels and the association between IHD and HDL cholesterol and genotype.

Heterozygote is a person possessing two different forms of a particular gene, one inherited from each parent.

The researchers found that heterozygotes vs. noncarriers with 4 ABCA1 had HDL cholesterol levels of 41 mg/dL vs. 58 mg/dL.

In CCHS, the risk of IHD in heterozygotes was 33 percent less, in CGPS the risk was 18 percent less and 14 percent lower in the CIHDS.

When these studies were combined there was no association between heterozygotes and a higher risk of IHD.

The study appears in June 4 issue of JAMA

ANI