TNFAIP8 and chronic obstructive pulmonary disease: In terms of the association between proteins and COPD subtypes, we found BTN1A1, Tumor necrosis factor alpha-induced protein 8 (TNFAIP8), Dystroglycan (DAG1), and Switch-associated protein 70 would decrease the risk of early-onset COPD risk (Fig. 2B).