After balancing the sensitivity and specificity of the ROC curve calculated from all non-HCC groups (n = 117) and all HCC groups (n = 95), the optimal cut-off of serum IgM-free AIM for predicting HCC was estimated to be 1.6 μg/mL as it showed the maximal diagnostic accuracy. This evidence concerns the gene CD40LG and hepatocellular carcinoma.