KLRK1 and cholangiocarcinoma: Compared to controls, PSC patients with killer cell lectin-like receptor K1 (KLRK1, encoding NKG2D) SNP rs11053781 and rs2617167 polymorphisms were more likely to develop CCA (OR = 2.08, 95% CI= 1.31~3.29, p = 0.011 and OR = 2.32, 95% CI = 1.47–3.66, p = 0.0020, respectively).