IRF1 and major depressive disorder: Therefore, the present study examines the prospective relationship between the occurrence, age of onset, severity or antidepressant treatment efficacy of MDD and appearance of single nucleotide polymorphism (SNP) located in inflammatory-related genes, that is, g.132484229C>A of IRF1 (rs2070729, located on 5q31.1), g.186643058A>G of PTGS2 (rs5275, located on 1q31.1), g.186640617C>T of PTGS2 (rs4648308, located on 1q31.1), g.70677994G>A of TGFA (rs2166975, located on 2p13.3), g.41354391A>G of TGFB1 (rs1800469, located on 19q13.2) and g.42140549G>T of IKBKB (rs5029748, located on 8p11.21).