THURSDAY, May 8 (HealthDay News) -- A gene called erythropoietin (EPO) is linked to severe diabetic eye and kidney diseases, a new study finds.

The study, led by a researcher at the John A. Moran Eye Center at the University of Utah, included 1,618 people with proliferative diabetic retinopathy (PDR) and end-stage renal disease (ESRD) and 954 diabetic patients without any eye or kidney disease.

PDR is the most common cause of legal blindness in working-age adults in the United States, accounting for 10 percent of new onset blindness overall. Diabetes is the leading cause of ESRD.

The researchers found that people with a copy of mutant EPO gene have an increased risk of developing PDR and ESRD.

"We know that the development of PDR and ESRD in diabetic patients can be inherited. Although genetic factors are known to be important in the susceptibility [or resistance] to these complications, until now, the genes involved have been mostly unknown," study leader Dr. Kang Zhang, director of the division of ophthalmic genetics at the Moran Eye Center and an associate professor of ophthalmology and visual sciences, said in a prepared statement.

The study was published online May 5 in the Proceedings of the National Academy of Sciences.

This finding may affect the use of EPO in treating patients with anemia, Zhang said.

EPO is used extensively to help in the production of red blood cells when treating patients with anemia resulting from renal failure or chemotherapy. In the United States, erythropoietin represents one of the largest single drug expenses for the Center for Medicare & Medicaid Services, approximately one billion dollars per year," Zhang said.

"Patients with anemia due to chronic renal disease [many of whom have diabetes] who receive frequent dosing of EPO to maintain higher hemoglobin levels have a higher rate of cardiovascular complications than patients who maintain a lower hemoglobin level. A similar effect of EPO on accelerating the decline of kidney function had been suggested by earlier studies. Our study suggests that caution may be warranted when maintaining higher hemoglobin concentration using exogenous EPO treatment in diabetic patients, as it might accelerate progression to PDR and ESRD."

Study co-author Dr. Dean Li, from the Program in Human Molecular Biology and Genetics at the University of Utah, added: "Though there is no proven pharmacologic treatment for diabetic vascular eye diseases, inhibiting the growth of unwanted blood vessel growth using antibodies directed against vascular endothelial growth factor [anti-VEGF therapy] has been advocated. This genetic study suggests that future therapeutic strategies need to consider blunting the effects of erythropoietin in addition, or as an alternative, to an anti-VEGF strategy."

More information

The U.S. National Eye Institute has more about diabetic eye disease.

-- Robert Preidt

SOURCE: University of Utah, news release, May 5, 2008

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