AOC2 (amine oxidase copper containing 2) is a copper-dependent enzyme that catalyzes oxidative deamination of primary amines to aldehydes, producing hydrogen peroxide and ammonia 1. Unlike related family members, AOC2 preferentially metabolizes larger monoamines including 2-phenylethylamine, tryptamine, and tyramine, with much lower efficiency toward methylamine and benzylamine 1. The enzyme is primarily expressed in retinal tissue, particularly in retinal ganglion cells, despite mRNA detection in multiple tissues 21. AOC2 belongs to the semicarbazide-sensitive amine oxidase (SSAO) family and shares structural conservation with related AOC family members, with specific active site residues (particularly a glycine at position X2) distinguishing it functionally from AOC1 and AOC3/4 subfamilies 34. Emerging evidence suggests AOC2 involvement in disease pathogenesis: it was identified as a cuproptosis-related hub gene in silicosis-associated immune dysregulation 5, included in metabolic dysregulation pathways in HIV-1-infected macrophages 6, and incorporated into prognostic models for colorectal cancer through regulatory T cell-related gene signatures 7. The true physiological function and disease mechanisms remain incompletely understood.