BACE1 and early-onset autosomal dominant Alzheimer disease: Interestingly, bisecting GlcNAc is highly prevalent in brain and has been detected as a post-translational modification on β-site amyloid precursor protein cleaving enzyme 1 (BACE1), influencing its intra-cellular localization and preventing its degradation.10,15 Since BACE1 is vital for Aβ production from the amyloid precursor protein, the presence of bisecting GlcNAc may play an early role in Alzheimer’s disease pathogenesis by preserving BACE1 activity and increasing Aβ production within the CNS.16