CYP1B1 and chronic obstructive pulmonary disease: Of the 47 genes altered in COPD cases, the top ten with the greatest fold changes were AHRR, CYP1B1, CYP4F2, CYP4F3, GAD1, LOC284825, MATN2, MCL1, MEP1A, and TPRXL (Fig. 4B).