Three hundred and fifteen women were offered an analysis of the genes ATM, BARD1, BRCA1, BRCA2, CHEK2, PALB2, RAD51C, and RAD51D. The median ages at breast cancer diagnosis and study invitation were 39.8 (IQR 38.5–39.9) and 51.5 (IQR 46.7–57.1) years, respectively. This evidence concerns the gene ATM and breast cancer.