Urea Cycle Disorders in the US and Europe – Evidence-based Clinical Outcomes Derived from Two Decades of Experience with Prospective Registry Studies

Background: Urea cycle disorders (UCDs) are a group of rare inherited neurometabolic diseases with an estimated cumulative prevalence of 1 in 35,000 to 52,000 newborns presenting with life-threatening symptoms within the first 28 days of life or with heterogeneous symptoms (e.g. developmental, neurological and intellectual disabilities) any time after the newborn period. Growing clinical awareness for UCDs, development of diagnostic and therapeutic recommendations, and the implementation of national newborn screening programs hold out the potential for improved clinical outcome.