Low-frequency loss-of-function mutations in iCCA are also found in APC (APC regulator of the WNT signaling pathway), BRCA1 (BRCA1 DNA repair associated), BRCA2 (BRCA2 DNA repair associated) [174,175], as well as NTRK fusions, which are reported in less than 1% of CCA patients [176]. Here, BRCA1 is linked to cholangiocarcinoma.