Leber's hereditary optic neuropathy is a rare disorder of the optic nerve which causes legal blindness in most patients that it affects. It is an unusual disorder in many ways. First, it is caused by a mutation in a small bit of DNA called "mitochondrial DNA." Since all of a person's mitochondrial DNA is inherited from their mother, the condition is only transmitted through females. However, not everyone who has the abnormal mitochondrial DNA suffers visual loss. In fact, even affected patients are perfectly normal for 10 to 50 years before the disease manifests itself as a sudden loss of vision first in one eye, and then a few weeks to months later in the second eye. Some patients eventually recover some of their lost vision even many years after the initial visual loss.
Patients with Leber's disease often exhibit a swollen optic nerve head (papilledema) and telangiectatic vessels.
In 1988, Dr. Douglas Wallace and his co-workers at Emory University in Atlanta discovered a mitochondrial DNA mutation in nine out of 11 families with Leber's hereditary optic neuropathy. This discovery allowed us and others across the country to test patients for the mutation and thereby confirm the diagnosis.
Research assistant Kim Vandenburgh loads DNA onto an agarose gel.
In 1990, our laboratory reported a new method of detecting the mitochondrial DNA mutation which was a substantial improvement over the old method. We have used this method to diagnose patients with Leber's hereditary optic neuropathy from across the country. We are currently participating in an international collaborative study designed to understand why some people affected with the mitochondrial mutation do not lose vision, and why some people who lose vision eventually get it back. We are hopeful that understanding these things will eventually allow us to develop effective treatment for this serious disease.
