Genetics And Glaucoma

Abstract

The recent advances of the human genome project have made genetic analysis of many human disorders possible. A genetic approach is especially productive when the quantity or accessibility of diseased tissues is limited. One aspect of the molecular approach that has been particularly important to glaucoma research is that only DNA from affected individuals and their relatives is required for analysis. Genetic approaches investigate the disease process at the DNA level and do not require samples of diseased tissues or even knowledge about how the disease may affect particular tissues. Collecting sufficient quantities of trabecular meshwork to perform biochemical and cellular studies, however, has been difficult. Moreover, tissue specimens taken from affected patients undergoing glaucoma surgery have been exposed to numerous medical and laser treatments that could obscure the initial abnormalities associated with the disease. Glaucoma research has been slowed because of the scarcity of trabecular meshwork and the inaccessibility of the retinal ganglion cells. Specific gene defects can be identified using DNA purified from lymphocytes obtained from a routine blood sample. The study of genes responsible for glaucoma will identify the role of specific protein products in the development of the disease without requiring direct access to ocular tissue. The identification of specific gene defects and the resulting abnormal protein products that are responsible for the various forms of glaucoma will help elucidate the underlying disease mechanisms. The identification and characterization of glaucoma susceptibility genes will also lead to new methods of diagnosis and treatment. The demonstration that the function of a particular enzyme or structural protein is impaired in glaucoma patients may lead to the development of new drug therapy. The identification of DNA sequence changes associated with the disease could form the basis of diagnostic tests useful for the identification of individuals at risk. The availability of such tests would provide a mechanism for early detection and treatment. Those individuals at risk who are identified early in the course of the disease and who begin therapy before significant damage to the optic nerve occurs will have the best chance of maintaining useful sight.