People with Down’s syndrome typically develop Alzheimer’s disease by middle age, including the amyloid plaques that are the hallmark of the disease. The extra copy of the Î²-amyloid precursor protein (APP) gene on chromosome 21 is thought to contribute to this neuropathology, but the precise mechanisms are unclear.
Writing in Cell Reports
(online, 23 October 2014), researchers led by Huaxi Xu, from Sanford-Burnham Medical Research Institute, La Jolla, California, say they have identified a key protein that regulates Î²-amyloid. Levels of “sorting nexin 27” protein are significantly reduced in people with Down’s syndrome, they say, which indirectly (via the gamma-secretase enzyme) promotes Î²-amyloid production and amyloid plaque formation.
“Our study establishes a molecular mechanism for Î²-amyloid-dependent pathogenesis in both Down’s syndrome and Alzheimer’s disease,” write Xu and co-authors.