MR Dictionary

Polygenic risk score approach

A method which combines multiple genetic IVs into a single univariate score, which can then be used as a single IV.

Traditionally used with individual-level data to generate the PRS and combined using one-sample MR methodology (e.g., two-stage least squares) but summary statistics from the PRS-exposure and PRS-outcome associations can be obtained and used to derive MR estimates with two-sample MR methodology (e.g., Wald ratio). The univariate score must be a valid instrument. More robust to weak instrument bias than two-stage least squares (TSLS). Hard to test for instrument validity.


Other terms in 'One-sample MR methods':