New genetic anomalies linked to breast cancer in African American families
Previously unknown segments of DNA shared by African American family members who have breast cancer have been uncovered by the “Jewels in our Genes” study. These results were published in the journals Cancer, Epidemiology, Biomarkers and Prevention (2014; doi:10.1158/1055-9965.EPI-14-1131)and the Journal of Community Genetics (2015; doi:10.1007/s12687-014-0199-8).
"The discovery of these regions supports our hypothesis that there are still undiscovered breast cancer genes that may be unique to African Americans," said lead researcher Heather Ochs-Balcom, PhD, a genetic epidemiologist in the University of Buffalo Department of Epidemiology and Environmental Health in New York. "We can now focus on these specific chromosomes to learn if they house genetic mutations linked to breast cancer.
"We also need to determine whether those mutations are found in other racial groups or if they are unique to African Americans. If they are unique, it could explain why young African American women have a higher risk of premenopausal breast cancer compared to other groups," she said.
Ochs-Balcom explained that the study used linkage analysis, which is a powerful tool that helps to detect the chromosomal location of disease genes by examining genetic markers across the entire human genome. She stated that this study is similar to the one done in the early 1990s that discovered the BRCA1 and BRCA2 gene mutations.
African American women can also carry the BRCA mutations, but Ochs-Balcom suspects there may be additional, undiscovered mutations linked to breast cancer in this population.
"Family studies like this one have been difficult to conduct in the past," Ochs-Balcom said, "in part because it's difficult to get multiple family members to commit the time needed to participate. We found here that approaching the recruitment of African Americans by using a multipronged approach that included collaboration from our community partnerships greatly facilitated success."
She points out that African American women have a higher incidence of premenopausal breast cancer and a higher breast cancer mortality rate than European Americans. They are also more likely to develop early onset cancers that are aggressive and difficult to treat. Some of these may be caused by unknown genetic anomalies that if found, could lead to early screening, detection, and treatment.
The study was funded by a grant from the Susan G. Komen for the Cure Foundation. It examined the DNA of 106 African American families not known to carry BRCA mutations tied to hereditary breast-ovarian cancer syndrome. Participants included 179 women who had been diagnosed with breast cancer and 76 of their sisters who never had the disease.
"Perhaps the most important motivating factor in their decision to participate in our study," said Ochs-Balcom, "was the potential to prevent suffering in their daughters and granddaughters."
She said the investigation itself was spurred by Veronica Meadows-Ray of Buffalo, an African American woman involved in Roswell Park's breast cancer survivor programs. Ray asked if a study could be undertaken to look into why her mother, aunt, and several cousins developed breast cancer although they do not carry the BRCA mutations. She suspected that their cancer was hereditary and provoked by genetic mutations unique to African Americans.