To express the trans-ancestry PRS on the same scale across ancestries and facilitate the selection of a single cutoff for clinical implementation of the PRS in prospective cohorts, we evaluated a regression-based ancestry adjustment method that builds on prior work [39, 40] and uses 1KG phase 3 data as the reference panel. Specifically, we calculated the PRS in the full 1KG dataset (N=2504), and assumed that both the mean and variance of the PRS depend on the top 5 PCs of the 1KG samples via two linear regressions:
