Aberrations involving specific chromosomes (2, 7, 11, 12, 15, 19, 22, and X) in the lymphocytes of breast cancer patients have been reported in a previous study.[20] Various genes involved in genomic stability and breast tumorigenesis [EP300 (22q13.2), LKB1 (19p13.3), FGFR1 (8p11.2), CHEK2 (22q) and K-ras (12p12)] are located in these regions and might be involved in the variable CIN phenotype. This evidence concerns the gene CHEK2 and breast cancer.