Most women know about the BRCA 1 and 2 gene mutations and how they significantly increase a woman's chance of developing breast cancer.
But they probably haven't heard of the rare genes PALB2 and ATM, which pose a similar risk - according to new research.
A large global study led by researchers at the University of Melbourne and Cancer Council Victoria has confirmed these genes increase the risk of breast cancer.
The risk of developing breast cancer is similar to that from the more common BRCA 1 and 2 mutations, says Professor Melissa Southey and Associate Professor Roger Milne, who led the international study of more than 200,000 participants from Europe, Australia, Asia and Africa.
About 55 to 65 per cent of women who inherit the BRCA1 mutation and around 45 per cent of women who inherit the BRCA2 mutation will develop breast cancer by the age of 70.
The findings, published in the Journal of Medical Genetics, will lead to new genetic screening, counselling and clinical guidelines, they say.
Prof Southey, of the University's Centre for Cancer Research at the Victorian Comprehensive Cancer Centre (VCCC) said a major challenge in cancer research is determining which genetic changes are connected to cancer risk.
Previous studies have highlighted PALB2 and ATM as genes of interest, but there hasn't been enough information to confirm their cancer risk.
"It's only by screening the DNA of tens of thousands of people in different countries that we have gained a clearer picture of their significance in causing cancers," said Prof Southey.
Assoc Prof Milne says the more they know about the different mutations, the closer they get to personalising treatments.
