Molecular genetics of age-related macular degeneration.

The numerous conditions that clinicians group under the term 'age-related macular degeneration' (AMD) are collectively the most common cause of severe visual loss in the developed world. Moreover, the number of people affected by these diseases is expected to nearly double in the next 25 years. A growing body of data suggests that a large fraction of AMD is caused by genetic factors. As a result, numerous investigators have sought genes that contribute to this disorder. At least six genes have now been identified that cause heritable macular disease, but none of these seem to cause even a moderate fraction of AMD. Affected pedigree member studies suggest that some regions of the genome do harbor AMD predisposing genes, but none have yet been identified by this approach. Studies of human donor tissue have yielded important new insights into pathways associated with AMD. These studies, when combined with the power of genetic approaches, are likely to ultimately reveal a set of genes responsible for a sizeable fraction of AMD.