The distributions of the percent mutant allele are similar for ER+ and ER- BRCA1 -associated breast cancers. The frequency distributions of percent mutant allele (m% values) for cases with insertion or deletion mutations in BRCA1 but excluding 1294 del40 cases (a) and the frequency distributions of NM_scores for cases with missense or nonsense point mutations (b) are shown for adjacent normal tissue samples (pink), ER+ tumor samples (blue), and ER- tumor samples (green). Distributions are calculated using all triplicate measurements from those samples passing quality assessment (that is, CV < 20%). In panel A, higher m% values indicate LOH with loss of wt BRCA1 allele (LOHwt) and lower values indicate LOH with loss of mutant BRCA1 allele (LOHmut). For panel B, lower NM_scores indicate loss of wt BRCA1 and higher NM_scores indicate loss of mutant BRCA1.