Twenty-four previously unknown mutations that raise a woman’s risk of developing breast cancer have been identified by scientists.
The ‘ground-breaking’ findings today provide an answer to thousands of victims of whom the disease runs in their family.
Mutations in known breast cancer genes are identified in only 20 per cent of women offered genetic testing for familial breast cancer.
But Australian scientists believe the new discovery ‘unlocks a big part of the puzzle’ and argue they should be looked for in tests.
The ‘ground-breaking’ findings today provide an answer to thousands of victims of whom breast cancer runs in their family
The University of Melbourne team claim their findings could allow doctors to better estimate a woman’s risk of getting breast cancer.
Figures suggest one in eight women will develop breast cancer in their lifetime in both the UK and the US.
However, Cancer Research UK states that fewer than three per cent of cancers are caused by an inherited faulty gene.
It says there are four known genes that can raise the risk of breast cancer, including the BRCA gene – famously carried by by Angelina Jolie.
But the new discovery, led by Professor Melissa Southey, could potentially extend that to 28, if further research confirms the findings.
She said: ‘For the majority of women who undergo genetic testing, there is no explanation for their breast cancer predisposition.
‘This ground-breaking 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.’
Commenting on the findings, Addie Mitchell, clinical nurse specialist at Breast Cancer Care, told MailOnline: ‘This fascinating study edges us closer to unpicking the complex relationship between family history and increased breast cancer risk.
‘Women regularly tell us they are hugely frustrated that genetic testing has left them with more questions than answers if a faulty gene isn’t found.
‘It will be really exciting if larger studies in the future reveal a new way to spot high-risk people who currently are under the radar.
‘However, it’s important to remember the greatest risk factors for breast cancer remain being a woman and getting older – not genes.’
Dr Eric Joo, study co-author, hopes more work will be done to develop tests to screen for the new markers associated with breast cancer.
He 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.’
Researchers looked at the genomes of 210 people from 25 multiple-case breast cancer families to make the findings.
They discovered the epigenetic changes can be passed down through generations without changing the DNA that makes the genes.
The study, published in Nature Communications, looked at DNA methylation – where chemicals modify DNA without changing its sequence.
DNA methylation – a process that controls how genes are expressed – can mimic genetic variation, predisposing a family to breast cancer.
The study is one of the first to scan the genome for places where DNA methylation is heritable, and is the first to apply this to familial breast cancer.
Experts believe their findings could open for the door and discover other currently unknown mutations that boost the risk of other heritable diseases.
Dr James Dowty, involved in the study, said: ‘Our methods were very successful when applied to breast cancer.
The statistician added: ‘And the exciting thing is that they can be applied to many other hereditary diseases.’