However, the prevalence of pathogenic germline BRCA1/2 variants in unselected Japanese patients with OC (27/230, 11.7%) did not show a large difference compared with that in other ethnicities, regardless of a large difference in prevalence of clear cell carcinoma, which showed a low frequency of pathogenic germline BRCA1/2 variants, between Caucasian and East Asian populations (including Japanese) [8, 12–22]. Here, BRCA1 is linked to clear cell adenocarcinoma.