Research identifies gene for major cause of cornea problem

Researchers have a identified a faulty gene that is the major cause of Fuchs’ corneal dystrophy, which affects an estimated 5% of Americans over the age of 40. The condition can ultimately cause blindness by blocking the transmission of light through the cornea. It is responsible for about a quarter of the 42,000 cornea transplants in the United States each year. People with one copy of the mutant gene are 5.5 times as likely to develop Fuchs’, while those with two copies are 30 times as likely.

The disease affects the endothelium, a thin layer of cells that line the back of the cornea. It starts as blurred or cloudy vision, then tiny bumps known as guttae form on the surface of the cornea. In severe cases, blisters form. There is no treatment other than a corneal transplant for severe cases. Previous research has identified defects that are associated with rare forms of the disease, but the new research reported Wednesday in the New England Journal of Medicine is the first to link a gene to the common form.

Dr. Albert O. Edwards of the University of Oregon and his colleagues studied the genomes of 280 Fuchs’ patients from Minnesota and Michigan, comparing them to 410 healthy controls. The researchers found a mutated form of the transcription-factor-4 gene (TCF4) in most of the patients with the disease, but only 2% of the healthy controls had two copies of the mutant gene.

Researchers don’t yet know much about the biochemistry of the disease, but identifying the causative gene is a major first step in that direction, co-author Dr. Keith H. Baratz of the Mayo Clinic said. “The ultimate goal is to find out how the disease occurs and find a treatment to prevent or slow its progression.�

-- Thomas H. Maugh II / Los Angeles Times