NCSTN and Alzheimer disease: ,11 In the context of AD, glycosylation affects the metabolism and function of several proteins implicated in AD pathogenesis, including beta-site amyloid precursor protein cleaving enzyme 1 (BACE1),12 tau,13, 14, 15 nicastrin,16 triggering receptor expressed on myeloid cells 2 (TREM2),17 and the amyloid precursor protein (APP).18