![Photo: Drawing of DNA](https://webarchive.library.unt.edu/eot2008/20090509202442im_/http://www.ars.usda.gov/is/pr/2009/dna0901.jpg)
A new study associates 11 new genetic sites with
cholesterol and triglyceride levels in people. Image courtesy of Microsoft
clip art.
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Gene Variants Affecting Blood Fats Identified
By Rosalie Marion
Bliss
January 26, 2009 A team of researchers has identified
new genetic sites harboring common variations in DNA that are linked to
imbalances in concentrations of blood lipids (fats). The findings provide
another step forward in understanding the genetic contribution to dyslipidemia,
a condition marked by overproduction of low-density lipoprotein (LDL
"bad" cholesterol) and triglycerides, and underproduction of
high-density lipoprotein (HDL "good"cholesterol).
The extensive research team included senior author and nutrigenomics expert
Jose
Ordovas of the
Jean
Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at
Tufts University in Boston, Mass. The HNRCA
is funded by the Agricultural Research
Service (ARS), a scientific research agency of the
U.S. Department of Agriculture. The study
was headed by Boston-based Massachusetts
General Hospital physician Sekar Kathiresan.
For the first stage of the study, the researchers analyzed data from seven
"genome-wide association" studies. Together, these studies provided
more than 2.6 million DNA markers, called single nucleotide polymorphisms, or
SNPs, from 19,840 individuals. These SNPs were then tested for associations
with lipoprotein traits.
The data from the first stage of the study confirmed previously reported
findings: Variants among eight earlier identified SNPs once again were
associated with lipid levels. The Stage One analysis also uncovered 25 other
DNA areas, or loci, of interest.
For the second stage of the study, the researchers genotyped SNPs in 20,623
individuals from five other studies, and looked further into the 25 promising
loci.
In a combined analysis of stages one and two, SNPs at 30 loci were
convincingly associated with all three blood lipids. These include a total of
19 previously identified loci confirmed in stage one, and 11 newly identified
loci associated with lipids.
While each of the 30 loci conferred a modest effect individually, the
analysis suggests that the more lipid-risk variants found in one individual,
the higher his or her association with dyslipidemia. Together, the 30 sites
explain a significant percentage of the genetic contribution to lipid levels
among individuals. More DNA sequence variants could be identified with larger
samples and improved statistical power for gene discovery, according to
authors.