To summarise previous reports, IDH mutations in cholangiocarcinoma have the following characteristics: (1) IDH1 mutations are more frequent than IDH2 mutations; the hotspot mutation of IDH1 is located at R132, while the hotspot mutation of IDH2 is located at R172; (2) the proportion of mutations is higher in ICC than in ECC; and (3) IDH1/2 mutations lose normal enzymatic activity and generate new activity, which can produce the oncogenic metabolite 2-hydroxyglutarate (2-HG). The gene discussed is IDH1; the disease is cholangiocarcinoma.