Searching for low-penetrance genes involved in breast cancer susceptibility has 
been a field of interest in the last few years. Recently, the CHEK 2 gene, 
involved in DNA damage and replication checkpoints, has been pointed out as a 
good candidate; moreover, a specific variant in this gene,1100delC, has been 
found to increase breast cancer susceptibility among familial breast cancer 
cases not attributable to mutations in BRCA1 or BRCA2 genes. In our present 
study, we evaluated the role of the 1100delC variant as a susceptibility allele 
in breast cancer in the Spanish population. However, our results suggest that 
this variant is absent or very infrequent in our population, making its 
screening irrelevant from the practical point of view.