Sample size and MTAG #251
Description
Hello,
I have a question regarding MTAG. We are studying a multi-trait GWAS of several disease-related outcomes, including clinical symptoms as well as surrogate outcomes such as imaging measures and plasma biomarkers (pairwise rg~0.2-0.5).
The GWAS for the clinical outcome has a sample size of approximately 500,000, whereas the surrogate outcomes (e.g., biomarkers) have much smaller sample sizes, at most ~10,000 or fewer.
Under this setting, would you recommend running MTAG jointly across all traits? Our concern is that the MTAG results may largely reflect the clinical outcome because it has the largest sample size, making it difficult to detect shared genetic architecture with the smaller biomarker traits.
Additionally, if we construct polygenic scores based on the MTAG results in this scenario, would they be expected to provide additional information beyond the clinical GWAS alone?
Thank you very much for your advice.