Since the model performance dropped little after eliminating cg15457058, cg07689503 and/or cg20172627 (Fig. 2C, Additional file 1: Table S6), the remaining 3 hypermethylated CpG sites, combined with AFP and DCP, were finally included for multitarget HCC diagnostic model training and verification. The gene discussed is AFP; the disease is hepatocellular carcinoma.