Figure 1
From: Integrating post-genomic approaches as a strategy to advance our understanding of health and disease
A causal model based upon Mendelian randomization. The model demonstrates the core assumptions for making a valid causal inference between a phenotype and disease. The three assumptions are: (1) genotype is independent of the confounder; (2) genotype is associated with phenotype; (3) genotype is independent of disease conditioning on phenotype and confounder. If these assumptions are valid, then an observed association between genotype and disease would imply the causality from phenotype to disease.