Scientists have shown that a protein involved in cholesterol metabolism may cause the accelerated onset of Alzheimer's Disease in individuals affected with Down Syndrome. People with Down Syndrome -- a genetic disorder due to the presence of an extra chromosome 21 -- develop Alzheimer's disease (AD) earlier (mid- to late 30s) than the general population (mid- to late 70s). To understand why, scientists have studied genes from chromosome 21 that are also involved in AD. One of those genes has already been found: It produces a protein called amyloid precursor protein (APP) that helps create protein clusters that are the hallmark of AD. Cheryl L. Wellington and colleagues have found another gene on chromosome 21 that produces a protein that regulates the amount of cholesterol present in a cell. The scientists showed that this protein influences the distribution and processing of APP and that it is present at high levels in the brains of Down Syndrome individuals. The new discovery may provide new ways to halt AD symptoms early in these individuals. Article: The cholesterol transporter ABCG1 modulates the subcellular distribution and proteolytic processing of beta-amyloid precursor protein Gavin H. Tansley, Braydon L. Burgess, Matt T. Bryan, Yuan Su, Veronica Hirsch-Reinshagen, Jonathan Pearce, Jeniffer Y Chan, Anna Wilkinson, Jeanette Evans, Kathryn E. Naus, Sean McIsaac, Kelley Bromley, Weihong Song, Hsui-Chiung Yang, Nan Wang, Ronald B. DeMattos, and Cheryl L. Wellington Published in the May 2007 issue of the