Table 1.

Peripheral blood DNA methylation detected in the BRCA1 promoter for the study groups

Group 1 (n = 52)Group 2 (n = 39)Group 3 (n = 164)Controls (n = 169)
≤1% Methylated alleles7244
>1% Methylated alleles6142
≥5% Methylated alleles3100
Not methylated3635156163
Proportion with BRCA1 promoter methylation16/52 (30.8%)4/39 (10.3%)8/164 (4.9%)6/169 (3.6%)

NOTE: The final methylation value for each individual was determined by assessing the relative methylation levels from MethyLight and MS-HRM experiments. Group 1 are women with 5 or more of 9 BRCA1 mutation-associated morphologic features, group 2 have 4, and group 3 have 3 or less. The complete data are shown in Supplementary Tables S1–S4.