Genetic Variation Cuts “Bad” Cholesterol, Reduces Heart Disease Risk
HOUSTON –(March 22, 2006)– People fortunate enough to have specific variations in a single gene enjoy moderately lower levels of “bad cholesterol” in their blood and significantly lower risk for coronary heart disease over their lifetimes, researchers from two University of Texas institutions report this week in the New England Journal of Medicine.
For the vast majority of people who don’t enjoy this genetic protection, the researchers note, the findings have an important lesson: early, consistent and moderate reductions in low-density lipoprotein would markedly reduce lifetime risk of coronary heart disease.
The study by scientists from The University of Texas Health Science Center at Houston and The University of Texas Southwestern Medical Center in Dallas looked at the impact of specific variations in the gene among 3,363 blacks and 9,524 whites over 15 years.
They found that variations in the gene reduced LDL by 28 percent among blacks, leading to an 88 percent reduction in coronary heart disease. A separate variation in whites was associated with a 15 percent reduction in LDL cholesterol and a 50 percent reduction in heart disease risk.
Only 2.6 percent of blacks had the protective variation in the proprotein convertase subtilisin/kexin type 9 serine protease gene (PCSK9 for short). Only 3.2 percent of white subjects had a separate variation in the same gene.
The project tapped long-term demographic, health and medical data, along with genetic samples, from the Atherosclerosis Risk in Communities (ARIC) project, which is directed by study co-author Eric Boerwinkle, Ph.D., who also is professor and director of the Center for Human Genetics at the Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, part of the UT Health Science Center at Houston.
“ARIC’s long-term information, coupled with its genetic samples, gave us the power to tease out the impact of this gene on human health and learn more about its potential as a therapeutic target to lower LDL cholesterol,” said Boerwinkle, who also is director of the Human Genetics Center at The University of Texas School of Public Health and holds the Kozmetsky Family Chair in Human Genetics.
“These data indicate that a moderate, life-long reduction in LDL cholesterol is associated with substantial reduction in the incidence of coronary events, even in populations with a high prevalence of other cardiovascular risk factors,” said Helen Hobbs, M.D., the study’s senior author, director of the Eugene McDermott Center for Human Growth and Development and an investigator in the Howard Hughes Medical Institute at UT Southwestern. She also directs the Donald W. Reynolds Cardiovascular Clinical Research Center at UT Southwestern. First author was Jonathan Cohen, Ph.D., professor of internal medicine at UT Southwestern.
LDL cholesterol can be reduced by lipid-lowering medications, exercise and diet.
Previous findings by Hobbs and colleagues at UT Southwestern had identified specific mutations in the PCSK9 gene that are associated with lower LDL cholesterol levels.
The precise mechanisms by which variations in the gene reduce LDL levels are not known, however research suggests that the variations reduce production of the PCSK9 enzyme, leading to reduction of LDL cholesterol.
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