DEFB1 and chronic obstructive pulmonary disease: Multiple studies have confirmed that single-nucleotide polymorphisms and copy number variations of DEFB1 and DEFB2 are associated with chronic obstructive pulmonary disease (COPD) and asthma.368–373 The ile38 variant (untranslated regions) of hBD1 was detected in 15.0% of patients, while only 2.8% of healthy individuals carried this variant.