THE UREA CYCLE DISORDERS CONSORTIUM: SETTING UP A MULTI-INSTITUTIONAL RESEARCH NETWORK IN RARE DISEASES Batshaw ML Children’s National Medical Center, Washington, DC The Urea Cycle Disorders (UCD) Consortium was established in 2003, funded through a grant from the Office of Rare Diseases Research and the National Institute of Child Health and Human Development of the NIH as one of the initial 10 Rare Diseases Clinical Research Centers. Starting with 5 sites in the U.S., it has evolved into an international consortium with 11 sites in the U.S., one in Canada and two in Europe. The additional sites have been funded primarily by philanthropy. The UCDC has a four-fold mission: 1) to perform collaborative clinical research including longitudinal studies of individuals with urea cycle disorders and clinical trials; 2) to train clinical investigators in rare diseases; 3) to perform pilot/demonstration clinical research projects; and 4) to provide access on a website to information related to UCD for basic and clinical researchers, academic and practicing physicians, patients and the lay public. This talk will describe lessons learned from developing this multi-institutional network and discuss some of the results that have come from these studies.