EPHX1 and chronic obstructive pulmonary disease: For the heterozygote model (OR = 0.885, PZ = 0.007), dominant model (OR = 0.886, PZ = 0.005) and allele model (OR = 0.906, PZ = 0.007), EPHX1 rs2234922 was found to be significantly associated with a lower risk of COPD, indicating that the G allele may be a protective factor for COPD.