An illustration of our approach to germline testing for deleterious variants on five genes (ATM, BRCA1, BRCA2, CHEK2, and PALB2) associated with increased risk of developing breast cancer, follows in the Results section, along with a broad exploration of the effects of varying parameter inputs (true penetrance, uncertainty in penetrance estimates, variant frequencies, relative (dis)utilities). This evidence concerns the gene ATM and breast cancer.