CHRNA5 and chronic obstructive pulmonary disease: The first genome-wide association study (GWAS) provided evidence of the association of the hedgehog interacting protein (HHIP), SERPINA, family with sequence similarity 13 member A (FAM13A), advanced glycosylation end-product specific receptor (AGER), cholinergic receptor nicotinic alpha 5 subunit (CHRNA5), and interleukin 27 (IL27) with COPD [6,7].