"Age-related macular degeneration (AMD) is the most common cause of irreversible blindness in the Western world. AMD has a strong genetic component, and it has been estimated that 50% of the heritability of AMD is explained by common variants in the complement system. Currently the first genetic tests based on a small number of common variants are being marketed, and new treatment modalities are being developed targeted to inhibit complement activation in AMD. However, genetic tests are not likely to be reliable since 50% of the heritability is still unexplained. In addition, studies by my group indicate that complement activation does not play a role in all AMD patients, so they will likely not benefit from treatments inhibiting the complement system.The goal of this proposal is to explain the “missing heritability” in AMD, and to better understand the pathogenic mechanisms underlying the disease. So far the role of rare variants in AMD has been neglected. Based on recent results from my group I hypothesize that a large proportion of the “missing heritability” in AMD is explained by rare, highly penetrant variants in genes that have not yet been associated with AMD. The first key objective of this proposal is to define the role of rare, highly penetrant variants in AMD. I also hypothesize that not only the complement system, but instead a generalized dysregulation of the immune system underlies the pathogenesis of AMD in certain subgroups of patients. The second key objective of this proposal is to understand the pathogenic mechanisms of immune system defects in AMD patients.The detection of rare genetic variants in the pathogenesis of AMD will allow a more accurate genetic risk assessment, enabling preventive measures in individuals at high risk. It will also provide more insight into the mechanisms that are involved in the pathogenesis of AMD, and will enable us to develop new therapeutic options for the diseases."