CYP27B1 and chronic obstructive pulmonary disease: The dominant model revealed a higher risk of COPD in patients with obesity (p = 0.014), overweight (p = 0.012), smokers (p = 0.024), former smokers (p < 0.001) and in carriers of the CYP27B1 rs4646536-AA genotype (p = 0.008).