New genetic marker for breast cancer identified

Washington, Mar 4 : Researchers at Memorial Sloan-Kettering Cancer Center (MSKCC) and the National Cancer Institute have discovered a new genetic marker for breast cancer which could help doctors detect the disease and help further research.

This international team of researchers, led by Kenneth Offit, MD, MPH, Chief of the Clinical Genetics Service at MSKCC, have also indicated that women having this DNA variation are at a 1.4 times greater risk of developing breast cancer in comparison to those without the variation.

"These results are exciting because they point us to new molecular pathways that may be associated with breast cancer," said Offit.

For the study, the researchers used a methodology called genome-wide association mapping, which looks at genetic variations across the entire genome that alter the individual building blocks of DNA makeup. These alterations may be more prevalent in individuals who have certain types of disease than in carriers without such disease.

The researches associated a new gene locus, a specific place on a chromosome where a gene is located, with breast cancer risk. This gene locus is on the long arm of chromosome 6.

"These research findings are of great interest because of the method of genome- wide association used to discover this new locus as well as others in recent months," said a co-author of the study.

The authors suggested that while the risk associated with this genetic marker is much lower than that of BRCA genetic mutations for example, this discovery would increase the understanding of the genetic variants responsible for breast cancer.

Samples were largely used from MSKCC, but the researchers also took them from other sites in the US, Canada, and Israel. All participants were of Ashkenazi (Eastern European Jewish) ancestry.

In the study, the researchers used a three-phase design centered on 249 families with multiple cases of breast cancer and no mutations of the BRCA genes.

"This newly identified genetic marker will not have any immediate clinical implications or impact on current screening guidelines for familial breast cancer. As such, a test for these markers is not available to the general public and these tests should be performed only as part of research studies," said Offit.

The researchers are now confirming that this risk marker is observed in other populations, and is studying possible changes in two genes in the chromosome 6q region.

The findings are published online in the journal Proceedings of the National Academy of Sciences.

ANI