What is PRS?

A Polygenic Risk Score (PRS) is a numerical value that represents an individual's genetic predisposition to a certain trait or disease, based on the cumulative effect of multiple genetic variants. These variants, typically single nucleotide polymorphisms (SNPs), each contribute a small amount to the overall risk, and PRS aggregates their effects to give an overall prediction.

Here’s how it works:

1. Genetic Variants: Researchers identify specific genetic variants that are associated with a particular trait or disease. These variants might not directly cause the condition, but rather increase or decrease the likelihood of its occurrence.

2. Weighting of Variants: Each genetic variant is assigned a weight based on its statistical association with the trait. This weight is often derived from large-scale studies, such as genome-wide association studies (GWAS), which look for correlations between genetic markers and diseases or traits in large populations.

3. Calculation of PRS: The individual’s genetic data is analyzed, and the PRS is calculated by summing the contributions (weighted values) of all relevant genetic variants. The higher the score, the greater the genetic predisposition to the trait or disease.

4. Risk Prediction: PRS can help estimate an individual's relative risk for diseases like heart disease, diabetes, certain cancers, and mental health conditions. It doesn't guarantee that someone will develop the disease, but it can indicate whether they are at higher or lower risk compared to the general population.

Use of PRS:

• Personalized Medicine: PRS can aid in predicting who might benefit from certain preventive interventions or treatments.
• Risk Stratification: It can be used by doctors to identify individuals who may need closer monitoring for particular conditions, even before symptoms appear.
• Genetic Counseling: For individuals with a family history of a disease, PRS can provide additional insight into their own genetic risk.

While PRS is a useful tool for understanding genetic risk, it's important to note that genetics is only one piece of the puzzle. Environmental factors, lifestyle choices, and other non-genetic factors also play significant roles in disease development.