GNAS and hepatocellular carcinoma: In this dataset, the level of anti-GNAS autoantibody in early HCC sera was higher than that in healthy controls (P < 0.05), as illustrated in Fig. 2A. Fig. 2B and Table 2 showed that the autoantibody to GNAS with an AUC of 0.798 can differentiate 64.0 % of early-stage HCC patients from healthy controls while the cut-off value designating positive reaction was set as the corresponding points to the largest Yueden's index when the specificity reached 80 %.