Genetic Defect Is Possible Link to Onset of Type 2 Diabetes

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Nov. 16, 1999 (Boston) -- Whether one person is more likely than another to develop diabetes may be "in the genes," Italian and American scientists have found. The researchers identified a genetic defect linked to insulin resistance -- a condition in which the body resists the effects of insulin and which usually precedes onset of type 2 diabetes. The discovery paves the way for genetic tests that could identify people at risk for type 2 diabetes. It may also lead to development of new drugs to restore the body's ability to regulate blood glucose (sugar) levels. The study was reported in a recent issue of Diabetes.

The genetic defect, dubbed the "Q allele," was found two to three times more often among people with insulin resistance or type 2 diabetes than among people with neither condition, report researchers Antonio Pizzuti, MD, and colleagues at the Instituto Scientifico Ospedale Casa Sollievo della Sofferenza in San Giovanni Rotondo, Italy, and Ira D. Goldfine, MD, of the University of California, San Francisco.

Type 2 diabetes occurs in about 25% of all people who develop insulin resistance, Goldfine tells WebMD. So the discovery could be very important for the prevention and treatment of type 2 diabetes -- and the heart disease and other complications associated with insulin resistance. "If you have insulin resistance, what you do is compensate by making more insulin, and the combination of high insulin and insulin resistance leads to ... hypertension ... abnormal clotting mechanisms, gout, etc.," says Goldfine, director of diabetes and endocrine research at UCSF-Mt. Zion Medical Center. People with type 2 diabetes also often go on to develop conditions associated with high blood glucose levels, Goldfine notes, including kidney failure, eye damage, and nerve damage.

The defect Goldfine and his Italian colleagues describe is a needle in a genetic haystack: the abnormal substitution of a single DNA particle out of 2,600 in the gene PC-1. Yet this one genetic defect has the power to interfere with the ability of insulin to regulate the way cells metabolize glucose.

A researcher who reviewed the study for WebMD says that although the discovery is interesting and might be important, it won't be translated into forms of treatment for some time. "This is not ready for prime time... but it's a very neat observation," says Robert A. Goldstein, MD, PhD, vice-president for research at the Juvenile Diabetes Foundation. "That genotyping [genetic testing] ... could identify people at risk for either type 2 diabetes or [coronary artery disease] is quite interesting."

The research was supported by grants from the American Diabetes Association, Juvenile Diabetes Foundation, and the Italian Department of Public Health.

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