Polygenic Risk Scoring

Most heritable conditions (heart disease, type 2 diabetes, certain cancers) are not caused by one faulty gene but by the combined weight of many small-effect variants spread across the genome. A polygenic risk score (PRS) aggregates those signals — typically from genome-wide association studies — into one number. The score predicts population-level risk, not individual destiny: a high score means elevated odds, not a diagnosis. The hard part is that the variant weights are estimated from study populations that are heavily European in ancestry, so scores transfer poorly across ethnic groups — a gap with direct clinical consequences.