They are essential for vision but they can not function or survive without RPE cells. It is not known why photoreceptors and RPE cells die in patients with macular degeneration, but it is probably due to a combination of genetic mutations that make the cells more susceptible to damage and exposure to damaging stimuli in the environment. One strategy is to identify the genetic defects that occur in patients with macular degeneration and then develop genetically engineered animal models that can be studied in detail. There are some forms of macular degeneration that occur in young patients due to a mutation in a single gene. Dr. Kang Zhang in the laboratory of Dr. Donald Zack is performing linkage analysis using DNA samples from patients with Stargardt's disease and has identified a new genetic locus where a defect exists in some patients.
Collaborative studies are underway to identify the gene in which the defect is located.
Collaborative studies in the Zack and Campochiaro laboratories are aimed at identifying proteins that interact with the product of the Best's disease gene product to try and identify its function and other studies are aimed at identifying genes that are good candidates for other retinal degenerations. The laboratory of Dr. David Valle is using a completely different strategy to identify candidate genes. In a large collaboration, the AMD Genetics Study, DNA samples are being obtained from patients with age-related macular degeneration and their affected family members. These samples are being used in a search for genes with defects and for candidate gene analyses. Environmental exposure Drs.