Among BRCA1/2-negative familial breast cancer patients, the prevalence of different CHEK2 germline mutations was reported with the frequency of 0% (0/25) in the French-Canadian population [4], 2.9% (15/507) in France [5], 5.8% (30/516) in Germany [6], 5.8% (10/172) in Ashkenazi Jewish population [7], 8.9% (8/89) in the UK, North America and the Netherlands [8] and 12.2% (10/82) in Finland [9]. Here, BRCA1 is linked to breast cancer.