Mutations in a gene called RECQL are strongly linked to the onset of breast cancer in populations of Polish and French-Canadian women, according to a study published in Nature Genetics (2015; doi:10.1038/ng.3284).

“Our work is an exciting step in identifying all of the relevant genes that are associated with inherited breast cancer,” said Mohammad Akbari, MD, PhD, of Women’s College Hospital of the University of Toronto in Ontario, Canada.

Approximately 10% of all breast cancer cases are hereditary, though it is believed that only half of all breast cancer susceptibility genes are known.

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In this study, approximately 20,000 different genes were studied among 195 breast cancer patients with strong family histories of breast cancer who did not have a mutation in BRCA1 or BRCA2. The patients came from two populations, a Polish group and a French-Canadian group, who are genetically very homogenous. Akbari then led the team that confirmed the association of the identified gene, RECQL, with breast cancer by studying 25,000 more patients and unaffected people from these two populations.

“This study showed that studying specific founder populations [such as] Polish and French-Canadian women is an excellent approach for identifying disease-associated genes,” explained coauthor Steven Narod, MD, FRCPC, FRSC, director of the familial breast cancer research unit at Women’s College Research Institute and a professor with the Dalla Lana School of Public Health at the University of Toronto.

Specific, recurrent RECQL mutations within both the Polish and French-Canadian populations were identified in this study. Within the Polish group, one type of RECQL mutation showed a five-fold increased risk for developing breast cancer compared to persons without a mutation. Meanwhile, within the French-Canadian population, another type of RECQL mutation occurred 50 times more frequently among familial breast cancer patients, compared to population controls.

Though RECQL mutations appeared to be quite rare, the authors observed a very high penetrance rate. This means that, in the populations studied, they estimate that up to one-half of women who have a mutation are destined to develop breast cancer. They expect that women from other countries will be studied shortly.

Akbari also supports the value of screening all women with breast cancer for genetic mutations, such as those occurring in RECQL. Based on a woman’s genetic profile, appropriate targeted therapies could be selected.

“In the future, we might be able to select or develop treatments that can work around or correct relevant genetic mutations that are linked to breast cancer,” explained Akbari. “This opens the door for new and better ways of approaching treatment.”