Support is requested for a Keystone Symposia meeting entitled Biology of Down Syndrome: Impacts Across the Biomedical Spectrum, organized by Victor Tybulewicz, Elizabeth Fisher, Thomas Blumenthal and Jeanne Lawrence. The meeting will be held in Santa Fe, New Mexico from January 24-27, 2016. Down syndrome (DS) arises from an extra copy of an entire human chromosome, 21 (Hsa21) (trisomy 21), resulting in a wide constellation of phenotypes; in addition to learning and memory deficits, there are greatly increased risks for congenital heart defects, early onset Alzheimer's disease, and leukemia. DS is a common disorder, with a prevalence of around 1 in 750 births, a frequency that is not diminishing, despite the availability of pre-natal diagnosis. It is the leading genetic cause of cognitive impairment. DS is a disorder of gene dosage for one or more of the ~300 genes on Hsa21, affecting many different systems, with variable severity and expressivity. Research into DS has recently come of age with the development of sophisticated cell and animal models, novel biological findings and clinical trials of therapeutics. Despite this growing research into DS and the number of people affected by it, there is no regular scientific meeting devoted to the syndrome. This interdisciplinary Keystone Symposia meeting brings together experts from disparate research fields (genetics, development, stem cell biology and neuroscience), all focused on the effects of trisomy 21. Of note, this meeting will be held during the same dates as Keystone Symposia meetings on Traumatic Brain Injury and Axons: From Cell Biology to Pathology, which will also be held in downtown Santa Fe, NM. Registered attendees of any one of these meeting may participate in sessions of the others, pending space availability.