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Mendelian Randomization (MR)

Definition
AI-generated

Mendelian randomization uses germline genetic variants as instrumental variables to estimate the causal effect of a modifiable exposure on an outcome, exploiting the fact that alleles are randomly allocated at conception—provided the instruments affect the outcome only through the exposure (no horizontal pleiotropy) and are independent of confounders.

Topics
Post-GWAS
Related
Causality Statistical Causality Collider Bias

Why it matters in GWAS

MR connects GWAS hits and summary statistics to causal questions about biomarkers and risk factors, but validity depends on instrument strength, lack of linkage confounding, and careful handling of pleiotropy and population structure.

Example usage

"We performed two-sample MR with LDL GWAS as exposure and CAD as outcome, using inverse-variance weighting and sensitivity analyses for pleiotropy."

Causality Statistical Causality Collider Bias Genome-Wide Association Study (GWAS) GWAS Summary Statistics Horizontal Pleiotropy Horizontal Pleiotropy (MR) Linkage Disequilibrium (LD) Single Nucleotide Polymorphism (SNP) Within-Family GWAS
Related-term network

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References

  • Davey Smith G, Ebrahim S. (2003). ‘Mendelian randomization’: can genetic epidemiology contribute to understanding environmental determinants of disease? Int J Epidemiol.
  • Uffelmann E, et al. (2021). Genome-wide association studies. Nat Rev Methods Primers. https://doi.org/10.1038/s43586-021-00056-9
← Mendelian law of inheritance Mesolithic Age →

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