CHEK2 and breast cancer: Subsequently, the idea of a distinct hereditary breast and colorectal cancer phenotype (HBCC) was proposed by Meijers-Heijboer and colleagues, when they found a significant association of the CHEK2 1100delC mutation with HBCC using a subset of familial breast cancer families that did not carry the BRCA1 or BRCA2 mutations [10].