Genetic testing may be key to helping rare eye diseases

Orlando-When a child receives the diagnosis of Leber's congenital amaurosis (LCA) or another genetically based disease, too often parents hear from the ophthalmologist that nothing can be done. Whether the doctor intends to deliver such a negative message or conveys it inadvertently by using cold, clinical terminology, it is the wrong message, according to Edwin M. Stone, MD, PhD.

"We should tell them that advances in genetic testing have given clinicians, patients, and parents several opportunities to take action," said Dr. Stone who delivered the Leonard Apt Memorial Lecture at the annual meeting of the American Academy of Pediatric Ophthalmology and Strabismus.

"What I want you to remember is that these people desperately need your help. They want to be involved in something. Let them fight back against the disease," Dr. Stone said. "Probably the thing that they most need in 2005 is some reason to have hope for an improved outcome. Of course, they also need a cure for the disease.

Rather than sending patients and families home to do nothing but wait for blindness to develop, Dr. Stone offered suggestions for more positive steps:

Such measures contribute to the efforts being waged in labs around the country and around the world to combat rare, genetic diseases, Dr. Stone said.

"Let's work together to make genetic testing available for everybody who needs it," he added, noting the many steps in this process.

"We have to find the genes that cause these diseases and understand those genes. We need to discover either naturally occurring genetic models or animal models of these diseases, or make them artificially. We need to try different kinds of treatments, whether gene replacement therapy or more conventional drugs," he said. "We then need to go out into the human population and find people who have these diseases so that we can enroll them in treatment trials when we have reason to believe that the treatments will work."

Fifteen years ago the bottleneck in treating genetic diseases was finding the genes, Dr. Stone said. Since then, genes linked to many diseases have been identified.

"We are in a new era, and I am going to argue that today the bottleneck or rate-limiting step is affordable screening of the human population to identify individuals who have these genetic abnormalities," he continued.

The vast majority of children with rare diseases and their families lose contact with the ophthalmologist after learning that little or nothing can be done, Dr. Stone said, but he stated that they must be located and enrolled in trials.

"We have to engage them in this fight because a lot of the things we want to do are sort of a numbers game. These diseases are so rare we don't have the luxury of running off 90% of our folks."

He also predicted that genetic testing will be offered almost exclusively through physicians and scientists who are interested in these diseases, because there are too few cases diagnosed each year to make it profitable for businesses to develop testing methods. While testing cannot be done for free, it can be offered through a non-profit model such as that used at the University of Iowa (see http://www.carverlab.org/ for more information).

In addition to the human outreach of offering patients and families ways to get involved, genetic testing will be the key to developing treatments, Dr. Stone said.