98th Annual Meeting DOG 2000

R 435

New approaches to identify genetic factors in monogenic and complex retinopathies

H. Stöhr, A. Gehrig, N. Mah, H. Schulz, B. H. F. Weber

In recent years concerted efforts have led to the cloning of more than 45 genes implicated in retinal disease. Nevertheless, the elucidation of the genetic causes of the estimated 200 disorders with an involvement of some form of retinal dystrophy is still a subtle task in ophthalmogenetic research. In particular, this applies for conditions where the use of traditional genetic approaches is limited and includes simplex cases without a family history of the disease and most importantly, the complex late onset age-related macular degeneration (AMD). AMD is a multifactorial disorder caused by environmental as well as genetic factors. Thus far, the strategy to search for susceptibility genes in AMD has mostly been confined to the mutational analysis of genes known to cause hereditary retinopathies with similarities to the AMD phenotype. To date, no major genetic component has been identified.

In general, any gene preferentially expressed in the retina/RPE represents a potential candidate for human retinopathies regardless of its function. To generate a large source of candidate genes we are aiming to systematically analyze expressed sequence tags (EST) available from retina cDNA libraries. This approach is based on the predicitive value of the in silico expression profile of established EST clusters that represent a single gene. These clusters are screened for their retina EST content and those showing a high level of representation in retina cDNA libraries are chosen for further expression analysis by RT-PCR and Northern Blot analysis. In addition, we use RPE cells detached from the choroid to construct a pure RPE enriched cDNA library by suppression substractive hybridization. The analysis of randomly selected clones will facilitate the isolation of RPE-specific genes. All novel genes exclusively or predominantly expressed in the retina/RPE complex will be analyzed for a possible association with AMD in a large collection of DNA samples from affected patients and ethnically- and age-matched controls.

Institut für Humangenetik, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074 Würzburg