PDCD1 and hepatocellular carcinoma: Moreover, it has been reported that PD1.1 and PD-1.6 polymorphisms combined with chronic HBV infection contribute to the development of HCC in a Chinese population (Li et al., 2013) and polymorphisms concur in the development of several tumor types and autoimmune disease pathogenesis (Momin et al., 2009; Liu et al., 2011; Tahoori et al., 2011; Li et al., 2013; Tang et al., 2017; Tejeda et al., 2017; Salmaninejad et al., 2018).