KYAT1 (kynurenine aminotransferase 1) catalyzes the transamination of L-kynurenine to form kynurenic acid (KA), a broad-spectrum antagonist of ionotropic excitatory amino acid receptors 12. Beyond tryptophan metabolism, KYAT1 metabolizes cysteine conjugates of halogenated compounds and catalyzes beta-elimination of S- and Se-conjugates, producing reactive metabolites 3. KYAT1 also participates in the glutamine transaminase-ω-amidase pathway, enabling metabolic flexibility under nutrient-limited conditions 4. In psychiatric conditions, KYAT1 expression is significantly altered. Plasma KYAT1 levels distinguish schizophrenia patients from healthy controls, with levels progressively restoring toward normal following paliperidone palmitate treatment 5. In depression, KYAT1 mRNA expression is significantly increased in the anterior cingulate cortex, suggesting astrocyte-mediated activation of the kynurenic acid pathway and potential links to glutamatergic dysfunction 6. Clinically, KYAT1 shows promise as a therapeutic target in cancer. Se-methylselenocysteine combined with KYAT1 induction generates ROS-mediated cytotoxicity in hepatocellular carcinoma, particularly when combined with microRNA-guided specificity to spare normal hepatocytes 7. KYAT1 expression also correlates with liver steatosis in Prader-Willi syndrome as part of metabolic biomarker signatures 8. Proteomic analysis identifies KYAT1 as a discriminatory marker in ARDS and schizophrenia, supporting its role as a transition-associated biomarker for therapeutic monitoring.