Discordant pattern of BRCA1 gene epimutation in blood between mothers and daughters

Methylation of the promoter of BRCA1 gene in peripheral blood (epimutation) has been associated with increased risk for breast cancer. Some studies have indicated that this epimutation is of constitutional origin and hence it could potentially be transmitted across generations. We used methylation sensitive high resolution melting technique to measure methylation of BRCA1 promoter in blood samples from 226 healthy women from the Andean region in Salta province, northern Argentina. In total 29 (13%) of the women showed detectable methylation of this gene. The analyses of mother-daughter pairs in this study, showed discordant methylation of BRCA1 between generations, with mothers tested positive for BRCA1 methylation in blood having daughters without signs of BRCA1 methylation, and vice versa. Our results show that the BRCA1 epimutation is unlikely transmitted from mother to daughters and hence may be a consequence of environmental exposure.