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Figure 1

From: The integrity of the corticospinal tract and corpus callosum, and the risk of ALS: univariable and multivariable Mendelian randomization

Figure 1

Flow chart showing the process for the MR analyses. (A) The TSMR analysis was conducted to assess the association between specific neuroimaging phenotypes and the risk of ALS, as well as to fulfill assumptions 1 to 3. (B) The MVMR analysis was used to investigate the roles of various neuroimaging metrics within specific fiber tracts or the average values of the 21 white matter fibers in ALS. MR, Mendelian randomization; TSMR, two-sample Mendelian randomization; MVMR, multivariable Mendelian randomization; IVs, instrumental variables; GWAS, genome-wide association study; CST, corticospinal tract; GCC, genu of the corpus callosum; BCC, body of the corpus callosum; SCC, splenium of the corpus callosum; dMRI, diffusion magnetic resonance imaging; FA, fractional anisotropy; AD, axial diffusivity; MD, mean diffusivity; RD, radial diffusivity; MO, mode of anisotropy; PC1, the first principal component of fractional anisotropy; PC5, the fifth principal component of fractional anisotropy; IVW, inverse variance weighting method; SNPs, single-nucleotide polymorphisms.

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