Terashima et al. reported cases of three patients with BRCA1/2 germline mutations (BRCA1 mutation: BRCA2 mutation = 1: 2) among eighty Japanese patients with biliary tract cancer who met ≥1 of the following criteria: (1) hereditary breast and/or ovarian cancer (HBOC) testing criteria modified for biliary tract cancer; (2) revised Bethesda Guidelines (RBGs) modified for biliary tract cancer (modified RBG); (3) familial biliary tract cancer criteria; (4) criteria for young biliary tract cancer [49]. The gene discussed is BRCA2; the disease is biliary tract cancer.