A population-based study found the CHEK2/1100delC was present in 4.2% of unselected male breast cancer cases, more prevalent than the frequency of 1.1% in 1,692 controls (OR = 4.1, 95% CI: 1.2-14.3, p = 0.05) (38). This evidence concerns the gene CHEK2 and breast carcinoma.