IDH1 (isocitrate dehydrogenase 1), encoding a metabolic enzyme that catalyzes the oxidative decarboxylation of isocitrate to generate α‐ketoglutarate (αKG), is a driver gene of ICC (mutational frequency: ≈5–24%)[19, 20] and many other cancer types, such as low‐grade gliomas (≈70–80%) and acute myeloid leukemia (≈6–10%).[21] Missense mutations in the Arg132 codon are the most frequent type of mutation in IDH1. The gene discussed is IDH1; the disease is intrahepatic cholangiocarcinoma.