Indeed, although one study found that the Z allele of SERPINA1 gene was associated with COPD with an odds ratio of 1.17–1.74 [74], seven other GWAS or exome-wide studies did not find an association between COPD and the Z allele [75-81]; yet, the Z-AAT allele is strongly linked clinically to COPD [82]. This evidence concerns the gene SERPINA1 and chronic obstructive pulmonary disease.