A University of Michigan study pinpointed two interacting genes that, when defective, can greatly increase the risk of macular degeneration, the leading cause of vision problems in the elderly. Dr. Goncalo Abecasis is the University of Michigan School of Public Health Felix E Moore Collegiate Professor of Biostatistics and lead author of the report.  He credits much of the discovery's success to a new method of gene mapping that uses ancestry-matched controls from existing gene databases – something that had never been done before.