RNASEH2A and cholangiocarcinoma: The Cuproptosis Risk Score (CRS) for CCA based on these 10 genes was calculated using the formula: CRS = Exp(EFCAB1) × (1.43309) + Exp(CDADC1) × (0.63383) + Exp(RNASEH2A) × (-1.14489) + Exp(HAMP) × (-0.00037) + Exp(WNK4) × (0.52956) + Exp(WNT10A) × (0.00610) + Exp(FGFBP2) × (0.17787) + Exp(ELAC1) × (-0.14684) + Exp(AGTR1) × (0.04918) + Exp(LBX2) × (0.28862).