In a historic milestone for African biomedical research, scientists have discovered two previously unknown genetic variants associated with breast cancer in Black South African women, marking a major step forward in efforts to close the global gap in genomic science.
The findings, published in Nature Communications, are the result of the first-ever genome-wide association study (GWAS) on breast cancer conducted within an African population. The research was led by the Sydney Brenner Institute for Molecular Bioscience (SBIMB) at the University of the Witwatersrand, placing Africa firmly at the centre of the next frontier in cancer genomics.
The study identified two new breast cancer susceptibility gene regions—RAB27A and USP22—that had not been previously linked to the disease. The discovery could lead to new, ancestry-specific diagnostic tools and precision therapies for women of African descent, who have historically been underrepresented in global genetic research.
“This discovery underscores how limiting it is to rely on one segment of the world’s population for understanding complex diseases,” said Dr. Mahtaab Hayat, lead author of the study. “It’s a call to action for science to reflect the full scope of human diversity.”
The team analysed DNA from Black South African women with breast cancer enrolled in the Johannesburg Cancer Study, comparing their profiles to cancer-free individuals from the AWI-Gen project, a pan-African genomic cohort.
One of the most critical insights from the study was the poor performance of polygenic risk scores (PRS)—tools that estimate disease risk based on genetics—when applied to African women. Developed using predominantly European datasets, these scores failed to accurately predict cancer risk in the African cohort.
“In African populations, these scores don’t work well. That failure is a direct consequence of scientific neglect,” said Dr. Jean-Tristan Brandenburg, co-author of the study. “Without ancestry-specific data, we are giving inaccurate health assessments to millions.”
The newly identified genes are believed to play pivotal roles in tumour growth and cancer aggressiveness. RAB27A is linked to cellular mechanisms that influence tumor progression, while USP22 is highly active in more aggressive breast cancer subtypes.
“If future research confirms these as drivers of disease, they could become critical drug targets,” said Prof. Chris Mathew, a senior investigator on the project. “This could lead to more effective, less toxic treatments for women who urgently need them.”
With breast cancer remaining the most common cancer among women worldwide—and the second most diagnosed cancer in South Africa—the findings could significantly enhance early detection and individualised treatment approaches across the continent.
Beyond medical innovation, the study underscores the immense value of Africa’s genetic diversity—an often overlooked but vital resource in global health research.
“Globally, we are only scratching the surface of what African genetics can reveal,” Hayat said. “This study proves that even in well-researched diseases like breast cancer, there is still so much to uncover when African voices are part of the scientific conversation.”
Researchers are now calling for increased investment in African-led research, infrastructure, and the training of local scientists to sustain this momentum and unlock further discoveries.
The study not only brings Africa closer to the global forefront of genomic science but also delivers a clear message: inclusive science is better science, and lifesaving innovation starts with representation.
Article by Nyokabi Wanjiku
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