Cited by 555Genetic Associations and EpidemiologyAdvanced Causal Inference TechniquesStatistical Methods in Epidemiology

Methodological Challenges in Mendelian Randomization

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VanderWeele, Tyler J., Tchetgen Tchetgen, Eric J., Cornelis, Marilyn, Kraft, Peter·2014·Epidemiology

Abstract

We give critical attention to the assumptions underlying Mendelian randomization analysis and their biological plausibility. Several scenarios violating the Mendelian randomization assumptions are described, including settings with inadequate phenotype definition, the setting of time-varying exposures, the presence of gene-environment interaction, the existence of measurement error, the possibility of reverse causation, and the presence of linkage disequilibrium. Data analysis examples are given, illustrating that the inappropriate use of instrumental variable techniques when the Mendelian randomization assumptions are violated can lead to biases of enormous magnitude. To help address some of the strong assumptions being made, three possible approaches are suggested. First, the original proposal of Katan (Lancet. 1986;1:507-508) for Mendelian randomization was not to use instrumental variable techniques to obtain estimates but merely to examine genotype-outcome associations to test for the presence of an effect of the exposure on the outcome. We show that this more modest goal and approach can circumvent many, though not all, the potential biases described. Second, we discuss the use of sensitivity analysis in evaluating the consequences of violations in the assumptions and in attempting to correct for those violations. Third, we suggest that a focus on negative, rather than positive, Mendelian randomization results may turn out to be more reliable.

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  • The exclusion restriction is sometimes also referred to as an assumption of no horizontal pleiotropy, but it can be violated in several other ways, including by gene-exposure interaction, by having some form of time varying exposures, by measurement error in the exposure that is related to the instrument, or by a multi-component exposure.

    “The exclusion restriction is sometimes also referred to as an assumption of no horizontal pleiotropy (box 3), but it can be violated in several other ways (eg, by gene-exposure interaction, by having some form of time varying exposures, by measurement error in the exposure that is related to the instrument or by a multi-component exposure).59”

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Research works printed but not linked: 3

  1. [22]Pearl J Direct and Indirect Effects Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence 2001 411 420 Morgan Kaufmann San Francisco, CA
  2. [25]Wooldridge JM Econometric Analysis of Cross Section and Panel Data 2002 MIT Press Cambridge
  3. [37]Rothman KJ Greenland S Lash TL Modern Epidemiology 2008 Lippincott Philadelphia 3rd Edition

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Authors
VanderWeele, T. J., Tchetgen Tchetgen, E. J., Cornelis, M., & Kraft, P.
Affiliations
Harvard University (US)
Corresponding author
VanderWeele, Tyler J.
Venue
Epidemiology
Published
2014-05
Volume
25
Issue
3
Pages
427-435
ISSN
1044-3983 (ISSN-L)
OpenAlex
W2325761966
Cited by
555
References
44
Citations by year
2026: 26 · 2025: 52 · 2024: 82 · 2023: 70 · 2022: 58 · 2021: 48 · 2020: 44 · 2019: 33 · 2018: 43 · 2017: 31 · 2016: 24 · 2015: 31 · 2014: 11
FWCI
4.28
Type
journal article
Language
en
Open access
Locations
  • Epidemiology (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • National Cancer Institute (P01CA134294, R35CA197449)
  • National Institute of Allergy and Infectious Diseases (R01AI104459)
  • National Institute of Environmental Health Sciences (ES017876, R01ES017876, R01ES020337, R56ES017876)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic Associations and Epidemiology
  • Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
Keywords
Mendelian randomization, gene-environment interaction, reverse causality, measurement error, linkage disequilibrium, time-varying exposure, sensitivity analysis
MeSH terms
Genetic Markers, Genotype, Humans, Random Allocation, Sensitivity and Specificity, Bias, Mendelian Randomization Analysis, Gene-Environment Interaction

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