2.1 Study design
We systematically evaluated the causal association between
gut microbiota and the risk of MN
through a two-sample MR analysis. Figure 1 showed an overview of this
study design, which complied with three key assumptions: (1) the
instrumental variables were associated with exposures; (2) the
instrumental variables were not related to the confounders; (3) the
instrumental variables influenced the outcome only through exposures
[11]. The second and third assumptions were performed to ensure the
independence of this study, which could be detected by various
statistical methods.