With respect to KIR genes, the frequencies of KIR2DL2 and KIR2DS2 were significantly higher in younger HCC patients (28.8% versus 13.1%; P = 0.013; OR = 2.69 and 25.0% versus 11.5%; P = 0.024; OR = 2.57, respectively) (Table 4). Here, KIR3DL1 is linked to hepatocellular carcinoma.