DDHD1 and chronic obstructive pulmonary disease: This study compared the expression levels of AGR3, BCHE, CBY1, CHRM3, DDHD1, DMPK, EDEM3, EDN1, HSPA2, KPNA2, LGALS3, MAOB, PIK3CA, PURA, and TMCC1 between COPD and control groups and evaluated their predictive abilities.