High cholesterol levels are a major contributor to heart disease in particular atherosclerosis. High density lipoprotein (HDL) has an essential role in reducing cholesterol levels, and therefore has a cardioprotective effect. There is therefore a great deal of research into the genetic underpinnings that control HDL blood levels. Individuals with Tangier disease have essentially no HDL in the blood. Recently the mutation underlying this disorder was identified in the ABC transporter A1 (ABCA1) gene, which is essential for the first step in the synthesis of HDL. When both ABCA1genes become nonfunctional, Tangier disease develops. Given the ABCA1 transporter's essential role in HDL synthesis, researchers have theorized that mutations in one of the ABCA1 genes may alter HDL levels in the normal population. Anne Tybjrg-Hansen and colleagues at Copenhagen University Hospital now provide the evidence that indeed alterations in the ABCA1 gene affect HDL levels in the general population. The authors found that approximately 10% of individual with low HDL levels in the general population have a mutation or nucleotide modification in one of their ABCA1 genes. Furthermore, the researchers showed that the 4 out of 9 individuals with low HDL specifically carry 1 of the 2 mutations identified in families with Tangier disease. These data provide insight into the genetic changes that can contribute to variation of HDL in the general population and add to our current understanding of the variety of mechanisms that together contribute to increased or decreased susceptibility to cardiovascular disease.

An accompanying commentary places this study in the context of the function of the ABCA1 transporter and its impact on HDL production along with studies of the genetics and molecular mechanisms relating to Tangier disease.

TITLE: Genetic variation in ABC transporter A1 contr
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Contact: Laurie Goodman
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212-342-4159
Journal of Clinical Investigation
1-Nov-2004