Third, if BRCA1-methylated WBCs represent constitutional methylation, and BRCA1-methylated WBCs and breast cancer precursor cells share a common embryonic clonal origin, one would expect a similar allele-specific BRCA1 methylation profile [26] in WBCs and matched BRCA1-methylated tumors from the same individual. Here, BRCA1 is linked to breast carcinoma.