BRCA1 and breast cancer: Figure S1D shows an overview of the TD score and BRCA1/2 bi-allelic inactivation status in CHORD-positive cases. Since the majority of BRCA1-mutated patients are diagnosed with ER-negative BC, another use-case for the TD score would be in this specific subgroup [22]. Therefore, within ER-negative samples (n = 74) the sensitivity to detect BRCA1-type BC is 87.1% (27 out of 31) with a 51.2% specificity (22 out of 43) using a cut-off of ≥2 TDs.