IDH1 and cholangiocarcinoma: Gene alterations involving IDH (isocitrate dehydrogenase gene), FGFR (fibroblast growth factor receptor), BRAF (v-RAF murine sarcoma viral oncogene homolog B1),HER2 (human epidermal growth factor receptor 2) can decisively influence the proliferation and development of cholangiocarcinoma [5].