AOC1 (amine oxidase copper containing 1) encodes diamine oxidase (DAO), a copper-containing enzyme that catalyzes the oxidative deamination of primary amines, particularly diamines like histamine and putrescine, producing aldehydes, hydrogen peroxide, and ammonia 1. The enzyme plays a critical role in histamine degradation and polyamine metabolism, with variants associated with reduced DAO activity leading to histamine accumulation and various neurological, gastrointestinal, and dermatological disorders 1. In kidney injury, AOC1 expression increases dramatically across multiple pathological conditions, contributing to polyamine breakdown and tissue damage responses 2. The gene shows tissue-specific and context-dependent roles in cancer: it acts as a tumor suppressor in prostate cancer by promoting ferroptosis through spermidine metabolism 3, while functioning as an oncogene in colorectal cancer by promoting proliferation and metastasis 4. AOC1 expression is transcriptionally regulated by factors like SOX15 3 and miR-424-5p 5, and serves as a prognostic biomarker in various cancers including hepatocellular carcinoma 6 and gliomas 7. The enzyme's involvement in polyamine metabolism positions it as a key regulator of cellular stress responses and tissue homeostasis.