Research Paper Volume 15, Issue 23 pp 14039—14065

Figure 1. Overview and assumptions of the Mendelian randomization study design. The MR design was used to explore the causal association between four groups of risk factors and OSA, including lifestyle, serum parameters, metabolic comorbidities and sex hormones. The MR design satisfies three major assumptions: MR I, SNPs are strongly correlated with risk factors; MR II, SNPs are irrelevant to confounders; MR III, SNPs affect outcome merely via exposure. Abbreviations: IV: instrumental variable; SNP: single nucleotide polymorphisms.