In order to quantify this observation, we correlated the proportion of cancers per organ which arise in BRCA1 and BRCA2 mutation carriers29 with the WID-OC-index of the respective normal tissue and found correlations of 0.23 (p = 0.22) and 0.43 (p = 0.019) in BRCA1- and BRCA2-driven cancers, respectively (Fig. 4g, h). The gene discussed is BRCA1; the disease is cancer.