The frequency of alterations, including mutation, deletion, amplification, and multiple alterations, for NHEJ pathway genes in HCC was found to be 17.6% by TCGA and 10% by AMC (Additional file 1: Fig. S2); in contrast, the frequency of alterations in the XLF gene was extremely low in HCC. This evidence concerns the gene NHEJ1 and hepatocellular carcinoma.