A collaborative study led by researchers at the John A. Moran Eye Center at the University of Utah has uncovered a gene called erythropoietin (EPO), which is associated with an increased risk of severe diabetic eye and kidney diseases, known as retinopathy and nephropathy.
Dr. Kang Zhang, the Director of the Division of Ophthalmic Genetics at the Moran Eye Center, led the research team that compared 1,618 people with proliferative diabetic retinopathy (PDR) and end-stage renal disease (ESDR), and 954 diabetes patients without any eye or kidney disease in three separate populations.
They found that people having a copy of mutant EPO gene had an increased risk of developing PDR and ESRD during their lifetime.
As to how important the finding is, Dr. Zhang said: "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."
While explaining the current use and cost of EPO for disease prevention, and how the new finding may affect its use, Dr. 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 $1 billion a year. Patients with anemia due to chronic renal disease (many of whom have diabetes) who receive frequent dosing of EPO to maintain higher haemoglobin levels have a higher rate of cardiovascular complications than patients who maintain a lower haemoglobin 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 haemoglobin concentration using exogenous EPO treatment in diabetic patients, as it might accelerate progression to PDR and ESRD," added the lead researcher.
Dr. Dean Li, a co-author from the Program in Human Molecular Biology and Genetics, said: "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."
Dr. Li added: "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."
The study has been published online in the journal Proceedings of National Academy of Sciences.