Presenilin-1 (PS-1) is a presenilin protein that in humans is encoded by the PSEN1 gene.[5] Presenilin-1 is one of the four core proteins in the gamma secretase complex, which is considered to play an important role in generation of amyloid beta (Aβ) from amyloid-beta precursor protein (APP). Accumulation of amyloid beta is associated with the onset of Alzheimer's disease.[6]