These polymorphisms were the Tyr113His and His139Arg in EPHX1, IL1RN variable number tandem repeat (VNTR) polymorphism, the GSTM1 null variant, Ile105Val (rs1695) in GSTP1, rs2241712/rs1982073/rs6957/rs1800470 in TGFB1, 308GA (rs1800629) in TNF and rs1799896 in SOD3. Furthermore, another gene IREB2 was also identified as a potential gene for COPD susceptibility [39,40]. Here, TNF is linked to chronic obstructive pulmonary disease.