In particular, an opposite mutation rate (higher for EGFR and lower for KRAS, MLH1 and GNAS genes) has been observed in ICC with chronic advanced disease compared to ICC with normal liver, while PIK3CA, PTEN, CDKN2A and TP53 mutations were found only in ICC developing on normal liver. The gene discussed is PIK3CA; the disease is intrahepatic cholangiocarcinoma.