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Researchers at the Sydney Brenner Institute for Molecular Bioscience (SBIMB) at the University of the Witwatersrand in Johannesburg, South Africa, have discovered two genetic variants that can be linked to breast cancer in black South African women.
“These genes have not been associated with the disease before, which is an important advance in understanding breast cancer risk and biology in women of African ancestry,” explained Mahtaab Hayat, PhD, lecturer at the University of the Witwatersrand (Wits) and the lead author of the study.
To date, the vast majority of breast cancer genetics research has been done in people of Asian and European descent, with only very few studies focusing on African ancestry and “limited primarily to African-American women, who largely descend from West African populations,” as stated in the press release.
The study, published in the journal Nature Communications under the title “Genome-Wide Association Study Identifies Common Variants Associated with Breast Cancer in South African Black Women,” is the first genome-wide association study (GWAS) on the continent to analyze breast cancer in African women living there.
For this particular GWAS, the researchers scanned for breast cancer and consistent genetic patterns in 2485 female black South African breast cancer patients participating in the Johannesburg Cancer Study. They compared their findings to 1101 women free of cancer in the Africa Wits-INDEPTH Partnership for Genomic Research study.
The researchers discovered two genetic variants in the black South African women enrolled in the Johannesburg Cancer Study. These variants centered around the gene USP22, which codes for the ubiquitin-specific peptidase 22 protein, is highly active in breast cancer cells, and has been linked to poor health outcomes, and the gene RAB27A, part of the RAS oncogene family that is involved in cell signaling pathways and cell growth and differentiation.
While the researchers state that further studies are needed to confirm the findings, the two genes, USP22 and RAB27A, could be potential targets for new precision anti-cancer drugs.
“We could potentially target harmful cancer cells while sparing healthy tissue, which is ideally what we want when administering cancer treatment,” emphasized Chris Mathew, PhD, Distinguished Professor at the SBIMB and a lead project investigator.
Moreover, if one of the genes were to be associated with poorer survival, it could potentially be used as a biomarker to predict patient outcomes and help physicians identify the most suitable treatments.
The researchers emphasized that although African populations are known to have more genetic variation than other populations worldwide, they are still greatly underrepresented in genomic research.
In their paper, they wrote: “The immense genetic diversity among the populations of sub-Saharan Africa and differences in environmental exposures between resident and non-resident African populations suggests that there may be substantial differences in the genetic determinants of cancer susceptibility both within continental Africa and across continents.
Bridging this knowledge gap is needed to increase our understanding of the genetic etiology of African breast cancer and to develop clinical tools […] that can guide screening approaches in Africa, and globally.”
With more detailed genomic knowledge of populations, treatments can become more precise in targeting and helping certain populations specifically.
“The study reveals that more people can benefit from genetic discoveries,” said Hayat. “It proves that new risk factors are still out there, waiting to be found.”