Gene to blame for some cases of age-related cataracts

Age-related cataracts account for 18 million cases of blindness and 59 million cases of reduced vision worldwide. In the United States, an estimated $4 billion is spent to treat the condition each year. The condition is known to be highly heritable; yet even after decades of research, little had been found about its genetic causes.

Recently, however, a collaborative investigation that included 10 laboratories from the United States, the United Kingdom and Australia elucidated the first gene associated with the formation of age-related cataracts. The study was led by Bing-Cheng Wang, PhD, professor of pharmacology at Case Western Reserve University School of Medicine and senior staff scientist at MetroHealth Medical Center, and Sudha K. Iyengar

The lens of the eye is normally clear, allowing the transmission of focused light onto the retina. A cataract occurs when proteins become damaged and clump together—causing the lens to become cloudy and vision to become obscured. The EphA2 gene encodes an enzyme that plays a role in the repair of those damaged proteins. Dr. Wang and his team discovered that deletion of this gene causes lens proteins to become sticky. They form clusters that damage the structure and impair the clarity of the lens. The findings of this study were published in the July 31 issue of PLoS Genetics .

"So far, we have identified several specific mutations in human EphA2 that are associated with age-related cataracts," Dr. Wang says. "We plan to continue to search for additional mutations, as further studies will allow us to better understand the specific cellular processes by which EphA2 helps maintain lens clarity."

Researchers hope the identification of the underlying causes of age-related cataracts will point them in the direction of new treatments and prevention methods.