In order to test whether the breast cancer risk within the BRCA-mutation carriers might be associated with serum OPG levels we performed a linear regression analysis (adjusted for age and menstrual cycle day) of serum OPG levels and reported breast cancer risk associated with specific sites of mutations in the 222 samples for which we had exact information on the site of the mutation (Rebbeck et al., 2015). Here, TNFRSF11B is linked to breast cancer.