IDH1 and intrahepatic cholangiocarcinoma: Several early small studies observed the most common mutations in ICC within AT-rich interactive domain-containing protein 1A (ARID1A, 36%), isocitrate dehydrogenase 1/2 (IDH1/2, 36%), TP53 (36%), and Myeloid Leukemia and Chlamydia (MCL1, 21%) genes [41].