IDH1 and cholangiocarcinoma: The most common genetic alterations in CCA are IDH1 (30%), ARID1A (23%), BAP1 (20%), TP53 (20%), and FGFR2 gene fusions (14%) with less frequent mutations in PIK3CA, NRAS, and ERBB2, as assessed within a cohort of 195 patients by targeted sequencing of 410 cancer-associated genes [10].