PNPLA3 and chronic obstructive pulmonary disease: Interestingly, 25 DEGs were differentially expressed in human and ferret, but not mice (Table 3); among these genes uniquely modeled in ferrets were those previously determined to be relevant to COPD pathogenesis, with upregulation observed for IL-18, KL, SRXN1, TREM1 and downregulation observed for HAS1 and PNPLA3 [33–36].