In 2018, using a large hospital-based cohort of ovarian cancer patients (n = 934) and population-based controls (n = 1698), followed by a similar verification cohort (n = 607 patients and n = 1984 controls), we found low-level mosaic BRCA1 epimutations to be associated with an odds ratio of 2.2–2.9 for HGSOC, but no increased risk for other types of ovarian cancer [52]. Here, BRCA1 is linked to ovarian cancer.