IL6 and chronic obstructive pulmonary disease: Multiple studies showed that variations in the IL-6 gene promoter at rs1800796 (572 G > C), rs1800795 (174 G > C) and rs1800797 (597 G > A) are linked to IL-6 levels in serum as well as the occurrence, prevalence and development of several diseases including sepsis, chronic obstructive pulmonary disease, and hepatocellular carcinoma [15, 16].