BRCA1 and breast cancer: The CHEK2 variants included 2 patients with CHEK2 del5395, 1 patient with CHEK2 1100delc and 1 patient with CHEK 2 IVS2 + 1G > A. Additionally, one patient in the matched group of 3,884 healthy controls without breast cancer was found to harbor a variant in both CHEK2 and BRCA1 [35].