They found that 11% of those 146 patients had P/LP germline variants, including 6 patients with IHC carrying variants in BRCA1, BRCA2, MLH1, and MSH2; 3 patients with perihilar CCA carrying variants in BRCA2, MLH1, and POLE; and 6 patients with EHC carrying variants in ATM, BRCA2, MLH1, POLD1, and RAD51D. In another Japanese population study, whole genome sequencing was performed on 1292 patients with BTC, including IHC, EHC, gallbladder cancer (GBC), and ampulla of Vater carcinoma. Here, BRCA2 is linked to cholangiocarcinoma.