Notably, by the MR-Egger approach assessing the causal effect of FGF23 on MS, there was no evidence of horizontal pleiotropy (intercept = -0.003, p = 0.95), but the causal estimate (OR = 0.66) was accompanied by a wide 95% CI (0.21-2.03), indicating a comprised power (p = 0.49). Here, FGF23 is linked to myeloid sarcoma.