Group 1 BC cases (n = 61) showed no R337H noncarriers who were positive for XAF1 p.E134*, whereas 77% of the p.R337H carriers (62/81) also presented p.E134* (13 in C1, 20 in C2, and 29 in C3, corresponding to 76%, 79%, and 75% of BC in each subregion, respectively). This evidence concerns the gene XAF1 and breast cancer.