TF and amyotrophic lateral sclerosis: For conservative analyses, we found that iron [OR, 1.00; 95% confidence interval (CI), 0.90–1.11; p = 0.99), log-transformed ferritin (OR, 0.96; 95% CI, 0.77–1.21; p = 0.75), transferrin saturation (OR, 0.99; 95% CI, 0.92–1.07, p = 0.81), and transferrin (OR, 1.04; 95% CI, 0.93–1.16, p = 0.50) were not causally associated with ALS incidence using IVW method.