SLC4A1 and cholangiocarcinoma: Four genes, i.e., RHD, RHCE, SLC4A1 and ACHE have prognostic value in only one type of cancer, such as RHD (Rhesus blood group system) in OV, RHCE (Rhesus blood group system) in SARC, (Figure 3A), etc. However, none of the 33 blood group antigen genes have prognostic values in prostate adenocarcinoma (PRAD), cholangiocarcinoma (CHOL), pheochromocytoma and paraganglioma (PCPG); in addition, GYPE, from the MNS antigen system has no prognostic significance in all cancers (Figure 3F,G).