Remember BRCA1, APC, and p53? The association between rare variants in those genes and familial breast cancer, colon cancer, and multiple cancers, respectively, had been reported over 10 years ago. Initially, many scientists had assumed that more common variants in these and other genes that have high-risk variants associated with familial cancers exist that would convey a more moderate risk to their carriers. For most of the famous "cancer genes", however, that doesn't seem to be the case.

Jianjin Liu and colleagues from the Genome Institute of Singapore, the Karolinska Institute in Stockholm, and the University of Leeds, now report that CHEK2, a gene whose rare variants had been linked more recently to familial breast cancer, does not seem to have common variants linked to breast cancer either.

They studied the CHEK2 gene in a group of women in Sweden. They started by identifying common variants by determining the sequence of the gene in 92 postmenopausal women. Having found six common variants, they then compared their frequency in a group of approximately 1,500 women with breast cancer and another group of 1,500 women, of the same age and with similar lifestyles, without the disease.

The results found no link between women who had the common CHEK2 variants and an increased risk of getting breast cancer. We know that there are genetic factors that influence a women's breast cancer risk. However, the genetic variants responsible are proving very difficult to find, and so far the familial cancer genes have not turned out to help much.

SOURCE:
Public Library of Science (http://www.plos.org)