The odds ratio for a CHEK2 mutation was higher for cases with a positive family history (OR = 2.3, 95%CI 1.3–3.9, p = 0.003) than those with no family history of breast cancer (OR = 1.4, 95%CI 0.96–2.1, p = 0.06) (Table 3). Here, CHEK2 is linked to breast cancer.