Researchers discover new gene strongly linked to breast cancer
Worldwide, breast cancer is the most common cancer in women. In 2012, almost 1.7 million women were diagnosed with the disease, accounting for around 12% of all new cancer cases. It is estimated that around 5-10% of all breast cancer cases are hereditary, resulting from mutations in genes passed down from a parent. Mutations in the BRCA1 and BRCA2 genes are the most common causes of hereditary breast cancer. Women with BRCA1 mutations have an average 55-65% chance of developing the disease, while the average risk of breast cancer among women with BRCA2 mutations is around 45%.
A number of other gene mutations have been associated with hereditary breast cancer, including mutations in the ATM, CHEK2 and TP53 genes. However, it is believed that to date, researchers have only discovered half of the gene mutations associated with breast cancer development. Now, it is possible another one can be added to the list. Dr. Mohammad Akbari, of the University of Toronto and the Women's College Research Institute at Women's College Hospital - both in Canada - and colleagues have linked mutations in a gene called RECQL with onset of breast cancer among Polish and French-Canadian women.
50% of women with RECQL mutation will develop breast cancer
To reach their findings, the team used whole-exome sequencing to analyze around 20,000 genes among 195 Polish or French-Canadian patients with breast cancer who had a strong family history of the disease but who were free of BRCA1 and BRCA2 mutations.
The researchers say they chose Polish and French-Canadian women for the study because they are very similar genetically. In both of these populations, the researchers identified rare recurrent RECQL mutations. In order to confirm that RECQL mutations are linked to onset of breast cancer, the researchers assessed the genes of an additional 25,000 Polish and French-Canadian women with or without breast cancer.
From this, the team identified specific, recurrent RECQL mutations among both populations that were associated with greater breast cancer risk. For example, they found one RECQL mutation in Polish women that was linked to a fivefold increased risk for breast cancer, compared with Polish women without this mutation. In the French-Canadian women, the researchers identified a RECQL mutation that occurred 50 times more often among those with a family history of breast cancer than those without a family history of the disease.
The researchers note that although these RECQL mutations seem to be rare, the risk of breast cancer among women who have them appears to be very high. In their study, they calculated that around 50% of women with a RECQL mutation would develop breast cancer. Based on their findings, the researchers conclude that RECQL is a breast cancer susceptibility gene. Dr. Akbari adds:
Each newly-identified gene brings doctors closer to treating the disease in diagnosed patients and undiagnosed women who carry the mutation. There are many things we can do for them
