Contributions of genetics to our understanding of inherited monogenic retinal diseases and age-related macular degeneration.

Molecular genetics has contributed greatly to our understanding of inherited ocular disease. Prior to the development of recombinant DNA technology, basic and clinical scientists were limited to a description and classification of phenotypes based on morphology, biochemistry, and physiology. Progress was severely hampered by the dearth of genetic information. The pace of progress accelerated in the 1990s after the first disease-causing allele for retinitis pigmentosa was reported. The years 1990 through 2000 featured the identification and characterization of multiple gene alleles underlying retinitis pigmentosa and allied monogenic diseases. A second leap in our understanding occurred in the past year. Age-related macular degeneration-which was, until now, refractory to the identification of genes involving significant segments of the patient population-is finally yielding its secrets. However, some genes have no known function. Indeed this is the case for the majority of genes putatively identified by the Human Genome Project. Answers to these questions will come through an amalgamation of genetics, cell biology, physiology, and other disciplines. Collaboration among investigators in these disciplines is already occurring out of sheer fascination over this interesting and important topic. In the end, patients with inherited ocular disease will be the final and highly deserving beneficiaries.