Search for genetic key to corneal disease

Nov 8 2004

A new federal grant focusing on painful inherited visual disorders that scar the cornea will allow researchers to narrow the genetic cause of one type of corneal dystrophy and to offer improved diagnosis of this family of diseases.

The $1.1 million, three-year award by the National Eye Institute funds follow-up research on Thiel-Behnke Corneal Dystrophy by principal investigators Richard W.Yee, M.D., clinical professor, and Xinping Zhao, Ph.D., assistant professor, both of the Department of Ophthalmology and Visual Science at The University of Texas Medical School at Houston.

“Thiel-Behnke causes spots of varying shape – they can look sort of like a fingerprint or be a dense patch blocking out light – on the front layer of cells in the cornea,” Yee said. “Onset can occur as early as infancy, as late as adolescence, and is accompanied by a sharp, stabbing pain. The spots can be visually debilitating.” The cornea is the curved, transparent layer at the very front of the eye.

Yee, Zhao, and UT School of Public Health Human Genetics Center colleagues Stephen Daiger, Ph.D., and Lori Sullivan, Ph.D., previously narrowed the genetic cause of Thiel-Behnke to a short portion of DNA on chromosome 10. The NEI grant will fund an intensive effort to pinpoint the culprit variation among possible genes on that strip of the chromosome, clarifying the molecular cause of the disease.

Once treatable only by corneal transplantation, Thiel-Behnke is now treated by laser surgery but can still result in loss of vision, Yee said.

In addition to understanding the origins of Thiel-Behnke, Yee anticipates that the grant will allow his team to help diagnose other varieties of corneal dystrophy.

“There are many types of dystrophy and it's difficult to discern them just by looking at them,” Yee said. “Physicians will be able to send us blood samples of patients, which we can screen for known mutations using genetic markers – not just for Thiel-Behnke but for other dystrophies – and perhaps help with diagnosis.”

Interested physicians may call 713-704-1839 for further information.

Corneal dystrophies are relatively rare, but studying them will provide insight into genetic disease mechanisms. “They offer a unique opportunity to look at disease mechanisms in a tissue that is simple, clear, and heals very quickly,” Yee said.

Holder of the Joe M. Green, Jr. Chair in Ophthalmology at the Medical School, Yee is an innovative practitioner of refractive surgery to repair visual defects and serves as director of Corneal and External Diseases and Refractive Surgery at Hermann Eye Center in Memorial Hermann Hospital.