Table 4.
Frequency of BRCA methylation (dichotomized results) in BRCA1/2-related and sporadic breast carcinomas by methylation-specific multiplex ligation-dependent probe amplification
| Probe | BRCA1-C, total n = 39 (%) | BRCA2-C, total n = 33 (%) | Sporadic-C, total n = 80 (%) | Test statistica | P-value | Total (%) | Cutoffb |
|---|---|---|---|---|---|---|---|
| BRCA1.1 | 0 (0) | 2 (6.1) | 11 (13.8) | 5.833c | 0.019* | 13 (8.6) | >15% |
| BRCA1.2 | 32 (82.1) | 14 (42.4) | 22 (27.5) | 20.296c | 0.000009* | 68 (44.7) | >17% |
| BRCA1.3 | 5 (12.8) | 2 (6.1) | 11 (13.8) | 0.589c | 0.465 | 18 (11.8) | >15% |
| BRCA1 totald | 32 (82.1) | 14 (42.4) | 22 (27.5) | 20.296c | 0.000009* | 68 (44.7) | |
| BRCA2.1 | 30 (76.9) | 18 (54.5) | 10 (12.5) | 47.117c | 2.93°10−12* | 58 (38.2) | >19% |
| BRCA2.2 | 4 (10.3) | 3 (9.1) | 0 (0) | 8.153e | 0.005* | 7 (4.6) | >15% |
| BRCA2.3 | 22 (56.4) | 14 (42.4) | 2 (2.5) | 45.600c | 1.65°10−12* | 38 (25) | >15% |
| BRCA2.4 | 3 (7.7) | 4 (12.1) | 0 (0.0) | 8.153e | 0.005* | 7 (4.6) | >15% |
| BRCA2 totald | 30 (76.9) | 20 (60.6) | 10 (12.5) | 51.432c | 0.029* | 60 (39.5) |
Abbreviations: BRCA1-C Breast carcinomas from BRCA1 germline mutation carriers, BRCA2-C Breast carcinomas from BRCA2 germline mutation carriers, Sporadic-C Sporadic breast carcinoma
aPearson’s chi-square test or Fisher’s exact test for BRCA1-C and BRCA2-C together against Sporadic-C
bCutoff based upon highest methylation percentage detected in normal breast tissue from nonmutation carriers
cPearson’s chi-square test
d BRCA1-C and BRCA2-C total entails the number (and percentage) of samples showing methylation in at least one of the BRCA1 or BRCA2 probes, respectively
eFisher’s exact test
*Statistically significant (two-sided p value <0.05)