BRCA1 and ovarian carcinoma: In contrast, primary BRCA1 normal tissue methylation assessed in WBCs is not a rare event; it occurs as a low-mosaic phenomenon in 4% to 10% of adult women and newborn girls without cancer.19,26 A potential pathogenic role of mosaic methylations may be paralleled with an elevated cancer risk associated with mosaic germline pathogenic variants in BRCA1 as well as other tumor suppressor genes.27,28,29,30,31 The finding that BRCA1 methylation was not associated with a family history of breast/ovarian cancer was expected, considering the magnitude of the HRs reported.