Numerous polymorphisms, occurring within this gene [especially g.117803515 C > T—NOS1 (rs1879417) and c.1823C > T—NOS2 (rs2297518)], play an essential role in the development mechanism of various diseases, including Fanconi anemia, depression, stroke, gastric, and urinary bladder cancer35,37–40. The gene discussed is NOS1; the disease is major depressive disorder.