New method finds networks of genes behind obesity

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Overeating disrupts entire networks of genes in the body, causing not only obesity, but diabetes and heart disease, in ways that may be possible to predict, researchers reported on Sunday.

The researchers developed a new method of analyzing DNA and used it to discover that obesity is not only complex -- something already known -- but complex in ways that had not been previously understood.

"Obesity is not a disease that is the result of a single change to a single gene. It changes entire networks," said Eric Schadt, executive director of Genetics at Merck Research Laboratories.

His team identified networks of hundreds of genes that appear to be thrown out of kilter when mice are fed a high-fat diet.

"This network is completely rocked by exposure to a high-fat, Western-type diet," Schadt said.

They then turned to a database of Icelandic people being studied by Decode Genetics Inc and found people have the same networks.

The joint teams did a detailed study of 1,000 blood samples and almost 700 samples of fat tissues from some of the Icelandic volunteers.

This showed that people who have a higher body mass index, a measurement of obesity, have characteristic patterns of gene activation in their fatty tissues not seen in DNA taken from blood.