BTN1A1 and chronic obstructive pulmonary disease: We identify 7 COPD-associated proteins, of which 4 Septin − 8, CBG, BTN1A1, and DAG1 were negatively associated with COPD progression, whereas the remaining 3 (MICB_MICA, TIE-1, and G-CSF) were positively associated with COPD risk.