Two genes, FAM175A and SLX4, harbored damaging mutations in controls but not in cases (Table 2), consistent with other observations that mutations in these two genes do not predispose to breast cancer.17 Mutations in the known moderate-risk genes were too rare to yield meaningful gene-specific risk estimates, and the evidence for causality among these genes varies too widely to pool risk estimates. This evidence concerns the gene SLX4 and breast cancer.