According to a new study, mutations in known breast cancer genes such as BRCA1 and BRCA2 are only identified in 20% of women who are offered genetic testing for familial breast cancer, meaning it’s not completely based on genetic inheritance.
The study was published in Nature Communications and, in an attempt to understand the genetic links of familial breast cancer, researchers looked at epigenetic changes called DNA methylation, where methyl group chemicals modify DNA without changing its sequence.
The researchers identified in the participants 24 previously unknown epigenetic changes that alter a woman’s risk of breast cancer and can be passed down through generations without involving changes in the DNA sequence of genes.
It’s the first to systematically scan the genome for places where DNA methylation is heritable and is also the first to apply this to familial breast cancer.
University of Melbourne and Monash University (Australia) research fellow Dr Eric Joo said: “Some individuals know they come from a family with a lot of breast cancer but do not have a mutation in a known breast cancer gene. This study should help answer why some of those families have a lot of cancer. It’s very exciting to be unlocking part of a big puzzle.”
No explanation for breast cancer predisposition
Professor Melissa Southey, of the Department of Clinical Pathology at the University of Melbourne and chair of precision medicine at Monash University, said: “For the majority of women who undergo genetic testing, there is no explanation for their breast cancer predisposition.
“This groundbreaking work is not only helpful for women from families with many cases of breast cancer, it will improve breast cancer risk prediction for all women and pave the way for the development of epigenetic therapeutics for breast cancer.”
Can this be applied to other hereditary diseases?
Statistician at the University of Melbourne Dr James Dowty said: “Our methods were very successful when applied to breast cancer, and the exciting thing is that they can be applied to many other hereditary diseases.
“This work was the result of a very fruitful collaboration between molecular biologists and statisticians, like a lot of work in modern medical research.”