IDH2 and cholangiocarcinoma: The isocitrate dehydrogenase (IDH) gene is one such target, and research suggests that IDH mutations may be present in up to 50% of chondrosarcomas and are involved in the pathogenesis of several other malignancies (e.g., gliomas/glioblastomas, cholangiocarcinomas, and acute myeloid leukemia) [6,7].