GAD1 and chronic obstructive pulmonary disease: In this study, the PPI network analyses between m6A RNA methylation regulators and key COPD genes showed that IGF2BP3, FTO, ZNF217, METTL3, YTHDC1 and YTHDC2 could indirectly interact with some key genes, such as CYP1B1, CYP1A1, AHRR, AKR1B10, GPX2, EGF,GAD1, CCL2, MMP12 and ALDH3A1.