IDH1 and cholangiocarcinoma: The U2AF1 mutation (exon3: p.R53C, ParsSNP score = 0.59) that was discovered in one case was previously reported to be a somatic mutation in colorectal cancer.20 We also found an oncogenic IDH1 mutation (exon6: p.M182V, ParsSNP score = 0.52), which is rare in head and neck cancers but frequently occurs in glioma21 and cholangiocarcinoma, where mutated IDH1 is associated with insensitivity to histone deacetylase inhibitors, irrespective of the specific mutation.22