Specific variations of a gene may cause up to 20 percent of all type 2 diabetes (search) cases in white people, a finding that could lead to new treatments.

The gene called PTPN1 (protein tyrosine phosphatase N1) is found on human chromosome 20 (search), which researchers have long investigated for diabetes genes.

PTPN1 (search) produces a protein that affects insulin activity in the body, researchers say. “If you are making a lot of this protein, your ability to respond to insulin would be blunted, which would lead to higher glucose (sugar) in your bloodstream. If it is too high, that’s [type 2] diabetes,” says senior researcher Donald W. Bowden, PhD, a professor of biochemistry at Wake Forest University School of Medicine in Winston-Salem, N.C.

His report appears in the November issue of the journal Diabetes.

About 35 percent of whites have this type 2 diabetes-causing variant of PTPN1; nearly 45 percent have a protective version of PTPN1. Other variations seem to be neutral, researchers say.

The newly discovered variations of the PTPN1 gene are possibly a big contributor to type 2 diabetes among whites — but not the only gene responsible for diabetes. Blacks, for example, aren’t susceptible to the effects of this abnormal variant gene, says Bowden.

His research involved two studies of 575 white patients who had type 2 diabetes and end-stage kidney disease. He also studied 810 Hispanic volunteer families, finding “completely consistent” results as with the white patients, Bowden says.

The researchers say that based on population estimated risks, this variant gene may be responsible for the development of type 2 diabetes in approximately 17-20 percent of people with the condition.

By Jeanie Lerche Davis, reviewed by Brunilda Nazario, MD

SOURCES: Bento, J. Diabetes, Nov. 2004; vol 53: pp 3007-3012. News release, Wake Forest University School of Medicine.