Scientists identify gene linked to diabetes

Scientists have identified a variant of a gene that increases the risk for type 2 diabetes. The discovery could ultimately lead to new ways to treat the potentially life-threatening condition that affects about 13 million adults in the United States.

Also important to the finding, reported in this month's Nature Genetics by a team of investigators at the Whitehead Institute in Cambridge, Mass., is the idea that scientists are using the recent gene discoveries to identify susceptibility genes for myriad medical conditions. There are now more than 100,000 so-called SNPs, or single nucleotide polymorphisms, a one-letter difference in the alphabet of a gene.

In the study, Dr. Joel Hirschhorn, Dr. David Altshuler and Eric Lander found that people with a common variant in a gene called PPAR gamma have a 25-percent increased risk for adult-onset type 2 diabetes. This susceptibility gene appears in 85 percent of the population, and the findings from the new study suggest that this SNP may play a role in as much as 25 percent of all type 2 diabetics, Hirschhorn said.

The PPAR gene affects the development of fat cells, controlling what cells become fat tissue. It also plays a still-mysterious role after development, something scientists discovered because a relatively new class of diabetes drugs works directly on PPAR receptors.

Researchers have long suspected a genetic link to type 2 diabetes, and the PPAR gene was studied as one possible trigger. But many gene studies have relied on small groups of patients and nonrelated normal volunteers, which don't generally yield sufficient information to draw conclusions. The new findings come from a large study in which Whitehead scientists collected blood samples from 1,500 type 2 diabetics and 2,500 of their relatives.

These findings don't present an immediate treatment or a diagnostic test. But they do help scientists understand the disease process, a step that could lead to the development of new medicines.

"In addition to the implications for diabetes, this study serves to illustrate the importance of common genetic variations in human disease," said Lander, director of the Whitehead Institute's Center for Genome Research. "These variations may have a modest effect on individual risk but still affect a major portion of the human population."