Impaired oxidative detoxification capacity in MDD, ↓ capacity of GPx to defend from OS in PBMC of MDD patients; the up-regulation of Nrf2 and NF-κB and their down-stream targets MnSOD, CuZnSOD, and CAT indicate OS status in PBMCs of MDD patients. The gene discussed is NFKB1; the disease is major depressive disorder.