The function of ENSG00000189221 (MAOA, monoamine oxidase A) is as follows. Catalyzes the oxidative deamination of primary and some secondary amine such as neurotransmitters, with concomitant reduction of oxygen to hydrogen peroxide and has important functions in the metabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues (PubMed:18391214, PubMed:20493079, PubMed:24169519, PubMed:8316221). Preferentially oxidizes serotonin (PubMed:20493079, PubMed:24169519). Also catalyzes the oxidative deamination of kynuramine to 3-(2-aminophenyl)-3-oxopropanal that can spontaneously condense to 4-hydroxyquinoline (By similarity). {ECO:0000250|UniProtKB:P21396, ECO:0000269|PubMed:18391214, ECO:0000269|PubMed:20493079, ECO:0000269|PubMed:24169519, ECO:0000269|PubMed:8316221}.