As a result, 10 variants in 8 genes were graded as strong evidence of association with COPD risk, including: GSTM1 null/present, CHRNA rs16969968, rs8034191, and rs1051730, ADAM33 rs612709, SP-D rs721917, TNF-α rs1800629, VDBP 1F, HMOX1 L allele, and HHIP rs13118928. Here, HMOX1 is linked to chronic obstructive pulmonary disease.