Some scholars have studied the apoptosis of biliary epithelial cells in PBC, and their results showed that DNA fragments were increased in biliary epithelial cells in PBC patients and that the levels of apoptosis-inducing ligands associated with Fas, FasL, perforin, granzyme B, and TNF were significantly increased (33–35). The gene discussed is PRF1; the disease is primary biliary cholangitis.