BRCA1 and cancer: Overall, ascertainment through sequencing-based screening in the biobank cohort showed an empirical prevalence for BRCA1/2 expected pathogenic variants of 1:190, adjusted to 1:180 when controlling for relatedness up to the third degree.19,25 Consistent with other studies, HBOC syndrome–associated cancer rates were higher in women than in men and in BRCA1 carriers than in BRCA2 carriers.3,28 Unsurprisingly, those with prior clinical BRCA1/2 testing also had higher cancer rates than those without prior testing.