Â鶹Éçmadou

Polygenic risk scores (PRS) are emerging tools for predicting complex traits—adverse health outcomes influenced by environmental, acquired, and heritable factors. Given that complex traits account for the majority of the global health burden, PRS offer a unique opportunity to bring personalised care into primary care settings. While nearly 100 PRS have been developed to estimate breast cancer risk in women of European ancestry, only four have been tailored to African ancestry populations. This study—the second largest involving individuals of African ancestry and the first in South African women—highlights substantial genetic diversity across African populations, with notable differences even within subgroups such as West Africans. When a European-derived PRS was applied to genomic data from South African participants, it explained less than 1% of breast cancer risk, underscoring the limitations of cross-population PRS application. These findings have major implications for health systems, particularly in multicultural countries like Australia, where equitable access to precision medicine will depend on population-specific genomic tools.