Testing in the population based PROCAS breast cancer study identified PALB2 PGVs in 4/524 (0.76%) (OR = 4.01, 95% CI = 1.07–15.95, P = 0.071) and the CHEK2_c.1100delC PGV in 9/524 (1.71%) (OR = 5.46, 95% CI = 1.93–14.60, P = 0.0021), whereas testing of breast cancer index cases in the context of family history/early onset breast cancer only, detected PALB2 PGVs in 29/2,301 (1.26%) (OR = 6.65, 95% CI = 2.26–20.86, P = 0.0002) and the CHEK2 c.1100delC PGV in 34/2,301 (1.48%) (OR = 4.69, 95% CI = 1.88–11.12, P = 0.0002). This evidence concerns the gene CHEK2 and breast carcinoma.