RA affection appeared causally and significantly predictive of increased levels of CRP, whether examining through the IVW approach (β = 0.033, 95% CI = 0.026–0.040, P < 0.001) (Supplementary Material, Table S1) or the MRE approach (β = 0.027, 95% CI = 0.016–0.038, P < 0.001) with no evidence of horizontal pleiotropy (P = 0.132) (Table 2). The gene discussed is CRP; the disease is rheumatoid arthritis.