Bae SC, et al. - Authors evaluated if the vitamin D level is causally associated with risk of systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA). The inverse-variance weighted (IVW), no evidence of a causal association between vitamin D level and risk of SLE was yielded by weighted median and MR-Egger regression methods. Furthermore, the unlikeliness of directional pleiotropy to be biasing the result for SLE or RA was revealed by MR-Egger regression. Findings suggested consistency of the MR estimates from IVW, weighted median, and MR-Egger regression analyses. A causal association between the vitamin D level and SLE or RA was not supported by MR analysis.