CHAS Fellow Olufunmilayo I. Olopade set out to evaluate the performance of existing breast cancer predictions models among women of African ancestry. Termed flip-flop (change in direction of the risk association), it means that a variant is risk factor in one population but protective in another, affecting the performance of risk prediction models. Data from the genome-wide association study (GWAS) of breast cancer in the African diaspora, which included 3686 participants of African ancestry from Nigeria, USA and Barbados. Polygenic risk scores (PRSs) were constructed from the odd rations of four sets of susceptibility. The flip-flop phenomenon was observed among 30-40% of variants across the studies. The results shows that PRSs based on variants identified from prior GWASs conducted in women of European and Asian ancestries did not provide a comparable degree of risk for women of African ancestry.