A newly discovered gene mutation significantly raises a woman's risk of breast cancer and may be considered the third such inherited gene flaw known to science, researchers said Wednesday.
Women with mutations in the PALB2 gene face a one in three chance of getting breast cancer by age 70, said the findings in the New England Journal of Medicine.
The other two known gene mutations associated with breast cancer risk, BRCA1 and BRCA2, have been linked to a 55-65 per cent likelihood of developing breast cancer by age 70.
"Since the BRCA1 and BRCA2 mutations were discovered in the mid-90s, no other genes of similar importance have been found and the consensus in the scientific community if more exist we would have found them by now," said lead author Marc Tischkowitz from the Department of Medical Genetics at the University of Cambridge.
"PALB2 is a potential candidate to be 'BRCA3'."
Most cases of breast cancer are not passed down in families.
Only about five to 10 per cent of all breast cancer has been linked to BRCA1 and BRCA2 gene mutations, according to the National Cancer Institute.
It remains unclear how prevalent PALB2 is in the general population, but researchers suspect it is rare.
The research in the New England Journal of Medicine was part of an international collaboration between 17 different institutions in eight countries.
Scientists analyzed data from 154 families without BRCA1 or BRCA2 mutations, which included 362 family members with PALB2 gene mutations.
Women with rare mutations in PALB2 were found to have on average a 35 per cent chance of developing breast cancer.
Individual risk varied, however. Those with more cases of breast cancer in the family found themselves at higher risk.
PALB2 was first linked to breast cancer in 2007.
"Now that we have identified this gene, we are in a position to provide genetic counseling and advice," added Tischkowitz.
"If a woman is found to carry this mutation, we would recommend additional surveillance, such as MRI breast screening."