Genetics play a major role in predisposing infants to retinopathy of prematurity (ROP), a disease prevalent in premature infants that disrupts normal blood vessel development of the retina and can lead to blindness, researchers at Yale School of Medicine report in the November issue of Pediatrics.

"This is the first definitive study to show that genetic factors are a significant component of ROP, and to quantify the extent of that genetic contribution," said lead author Vineet Bhandari, M.D., assistant professor of pediatrics at Yale School of Medicine.

ROP is most prevalent and severe in extremely low birth weight newborns with an overall incidence estimated to be as high as 68 percent among those born at less than 1,251 grams (2.75 pounds), and 93 percent in those born less than 750 grams (1.6 pounds). Despite early detection and intervention, ROP may lead to retinal detachment and blindness. In an attempt to treat ROP, researchers have sought significant factors, such as too much oxygen, that contribute to the disease. The Yale team hypothesized that there was a strong genetic connection involved in developing ROP.

They looked at contributing factors and outcomes for ROP within 200 twin pairs born at 32 weeks gestation or less. Study participants were from Yale, the Karolinska Institute in Sweden and the University of Connecticut. These 200 twin pairs had a mean gestational age and birth weight of 29 weeks and 1,332 grams (2.9 pounds), respectively.

"Our analyses showed that gestational age and duration of supplemental oxygen were the significant independent contributing factors for ROP," said Bhandari. "Once significant non-genetic co-factors for ROP were identified, we calculated the genetic susceptibility and determined that 70 percent of the contribution to ROP was the result of genetic factors alone."

"The magnitude to which genetic factors contribute to this major cause of infant morbidity accentuates the need for a shift in the paradigm utilized to identify and treat this disease process," Bhandari added. "It is possible that a dual therapy for ROP aimed at limiting potential environmental risk factors and identifying and targeting specific genetic factors may become the model for future intervention."

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Other authors on the study included Matthew J. Bizzarro, M.D., Laura R. Ment, M.D., of the Department of Pediatrics at Yale; Jeffrey R. Gruen, M.D., of the Departments of Pediatrics and Genetics; Heping Zhang and Rui Feng of the Department of Epidemiology and Public Health at Yale; Naveed Hussain, M.D., of the University of Connecticut Health Center; and Baldvin Jonsson, M.D., of the Karolinska Institute.

Citation: Pediatrics, 118: 1858-1863 (November 2006)

Contact: Karen N. Peart
Yale University