[Challenges and factors that influencing causal inference and interpretation, based on Mendelian randomization...

Genetic variation is used as instrumental variable to investigate the causal relationship between exposure and outcome, which can avoid issues of confounding and reserve causation regarding Mendelian randomization studies. However, the instrumental variables in Mendelian randomization studies must satisfy three core assumptions-the relevance assumption, the independence assumption, and the exclusion restriction assumption. In addition to the plausibility of core assumptions, the application of Mendelian randomization studies in causal inference is also subject to other limitations. Findings from the Mendelian randomization studies should be interpreted in the context of existing evidence from other sources. In this article we provide an overview of the assumptions, limitations, and interpretation on causal inference that related to Mendelian randomization studies that can be applied in studies of the same kind.