Despite the fact that oncogenic mutations in CCA, such as TP53, KRAS, IDH1, ARID1A, and CDKN2A/B are commonly found in many other cancer types, it is apparent that the alteration frequencies differ substantially between intrahepatic CCA and extrahepatic CCA (eCCA) (Table 2). The gene discussed is CDKN2A; the disease is cholangiocarcinoma.