CHRNA5 and chronic obstructive pulmonary disease: Regarding CHRNA5 rs16969968, we found a nominally statistical association between SNP rs16969968 and COPD risk under the three genetic models in all populations (allelic model: OR = 1.307, 95% CI = 1.205–1.417, p < 0.001; dominant model: OR = 1.413, 95% CI = 1.268–1.573, p < 0.001; recessive model: OR = 1.370, 95% CI = 1.154–1.625, p < 0.001) and a nominal association under the allelic and dominant models in Asians (allelic model: OR = 1.591, 95% CI = 1.204–2.103, p = 0.001; dominant model: OR = 1.625, 95% CI = 1.222–2.160, p = 0.001).