To further validate the role of the GRK4 gene in COPD, we conducted a cross-tissue TWAS analysis in the COPD validation set, identifying 301 candidate genes with P < 0.05 (Supplementary Material 1, S9), among which 27 genes remained significant after FDR correction (PFDR < 0.05), as detailed in Table 3. The gene discussed is GRK4; the disease is chronic obstructive pulmonary disease.