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Genetic Variant Linked to Adult and Childhood Obesity

Polymorphism affects the fat metabolism gene INSIG2 and is found in 10 percent of individuals

FRIDAY, April 14 (HealthDay News) -- A common genetic variant found near the fat metabolism gene INSIG2 is linked to adult and childhood obesity, according to a study in the April 14 issue of Science. About 10 percent of people have the polymorphism and such individuals are 33 percent more likely to be obese than their same-age peers.

Alan Herbert, Ph.D., from Boston University Medical School, and colleagues used a pioneering statistical technique to identify the genetic variant. Using blood samples from participants in the Framingham Heart Study, they looked for associations between 86,604 single nucleotide polymorphisms, or SNPs, and patient body mass index (BMI).

The authors found that the variant occurs upstream of the INSIG2 gene, which encodes a protein that inhibits fatty acid and cholesterol synthesis. The SNP, known as rs7566605, had strong statistical correlation with BMI in four of five independent studies. Subjects homozygous for cytosine (CC) at rs7566605 had a BMI one unit higher than their peers who were GC or GG, regardless of age or gender. Frequency of the polymorphism was gauged by testing black and white populations, as well as adults and children.

The mutation could affect the function of INSIG2 but further research is required to establish a causative relationship. "Our study suggests that common genetic polymorphisms are important determinants of obesity," they write.

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