Figure 1.

Analytical schematic diagram of the Mendelian randomization (MR) analysis implemented in this study

(a) Univariable MR analysis; (b) multivariable MR analysis, including two models: (i) confounder model; (ii) pleiotropic model.

G represents genetic variants (single-nucleotide polymorphisms, SNPs) that reliably predict the exposure variable (X) and are used as instrumental variables to represent exposure. G₁ and G₂ represent SNPs that specifically affect X₁ and X₂, respectively, whereas G₁₂ represents SNPs that affect both X₁ and X₂ simultaneously. Thick lines illustrate the causal effect confirmed by the current analysis.

BMI, body mass index; WHR, waist-to-hip ratio; WHR_adjBMI, waist-to-hip ratio adjusted for body mass index; ER, oestrogen receptor.