After gene screening for AF (Figures 5B,C) and CKD (Figures 5D,E) by the LASSO algorithm respectively, the intersection was taken to obtain 7 characteristic genes: PPBP, CXCL1, C3, LRRK2, RGS18, HLA—DQA1, RSAD2. The gene discussed is C3; the disease is atrial fibrillation.