Study identifies two new breast cancer genes in African women

A new study has identified two previously unknown breast cancer genes in Black African women, marking a significant step forward in understanding the genetic risks of the disease in underrepresented populations.

Published in Nature Communications, the research identified two genetic variants, RAB27A and USP22, linked to breast cancer in Black South African women.

Dr Mahtaab Hayat, lead author of the study, said the findings provide critical insights into the genetic foundations of breast cancer in African populations, which have historically been excluded from large-scale genomic studies.

Led by scientists at the Sydney Brenner Institute for Molecular Bioscience (SBIMB), the study is the first genome-wide association study of breast cancer conducted among African women living on the continent.

Researchers scanned thousands of DNA samples and found consistent genetic patterns, particularly around RAB27A, a member of the RAS oncogene family, and USP22, a gene highly active in breast cancer cells and associated with poor prognosis.

“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,” Hayat said.

The research pointed out the importance of ancestry-specific genetic tools, as most polygenic risk scores, which are used to predict disease likelihood, were developed based on European populations.

Co-lead author Dr Jean-Tristan Brandenburg stated how the gap in data has led to less accurate risk prediction in African populations.

“Our study makes a compelling case for investing in genomic research rooted in African contexts,” Hayat said.

Globally, breast cancer is the most common cancer in women, with genetic factors contributing to roughly 30 per cent of cases.

In Kenya alone, it accounts for 23.3 per cent of all cancer diagnoses in women, with an estimated 6,799 new cases and 3,107 deaths annually, according to the National Cancer Institute of Kenya.

The institute recommends early detection through regular mammograms, self-examinations and maintaining a healthy lifestyle as key to effective treatment. Back at SBIMB, the team believes the newly identified genes could serve as drug targets for more precise therapies.

“We could potentially target harmful cancer cells while sparing healthy tissue, which is ideally what we want when administering cancer treatment,” said Prof Chris Mathew, SBIMB lead investigator.

Mathew added that genes like USP22, associated with worse survival outcomes, might serve as biomarkers to predict which patients need more aggressive care and closer monitoring.

The study also points out Africa’s rich genetic diversity, which is greater than that of any other continent but remains severely underrepresented in global genomic databases.

“The study reveals that more people can benefit from genetic discoveries. It proves that new risk factors are still out there, waiting to be found,” Hayat said.