BACE1 and Alzheimer disease: Aberrant alterations in glycosylation on amyloid precursor protein (APP) [3-7], beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1) [8], presenilin (PS), nicastrin, microtubule-associated protein Tau [9-11], cholinesterase (AChE) [12, 13], and transferrin (Tf) [14, 15] have been demonstrated in AD [16].