Directed acyclic graph of a Mendelian randomisation study. (IMAGE)

First Hospital of Jilin University

Directed acyclic graph of a Mendelian randomisation study.

Caption

Nodes are presented in boldface and labelled paths represent the effects between nodes. G represents a genetic variant, X the exposure, Y the outcome and C (potential unmeasured) common causes of X and Y. Instrumental variable assumption. (1) Relevance: genetic variant G is associated with the exposure X; (2) independence: the association of genetic variant G and the outcome Y is not confounded; (3) exclusion restriction: genetic variant G does not affect the outcome Y except through its effect on the exposure. The causal effect of interest is the exposure on the outcome Y, depicted in solid red lines.

Credit

By Shan Luo, Ming-Hua Zheng, Vincent Wai-Sun Wong, Shiu Lun Au Yeung

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License

CC BY-NC

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