Polygenic Risk Scores

  • Each individual has millions of genetic variants and some of these can modestly increase the risk of developing a health condition.
  • These variants are common and have low penetrance, each having a small effect. However, when added together they can be associated with a high risk of developing a condition.
  • A polygenic risk score (PRS) is estimated by adding up the genetic risk from common variants and is used to help estimate the overall risk someone has of developing a health condition.
  • PRS results are reported for all conditions, except colorectal cancer.
  • PRS results are based on what we currently know about genetic factors that influence a person's risk for these conditions.
  • The risk scores were developed using mostly data from people of European descent, so they may not be equally effective at predicting risk in individuals with non-European ancestry.
  • Where possible, the PRS results have been validated (or confirmed) in people from four ancestral populations: Asian, African, European, and Hispanic/Latino.
  • Each PRS was validated using genetic information from other research studies with different populations.
  • If a participant's PRS is in the top 5%, as an example, they may have a significantly higher genetic risk for the condition than the remaining 95 out of 100 people.
  • A polygenic score is neither deterministic nor diagnostic. Some individuals with a 'not high risk' polygenic score can still be at risk of developing the disease or might have the disease. Some people with a 'high risk' polygenic score will never develop the disease.
  • Individuals with the same genetic risk can experience different outcomes depending on other variables such as lifestyle factors.

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