Within studies of the FCN1, FCN2, and FCN3 genes, Pieczarka et al. found an association between rheumatoid arthritis and the rs10120023 variant of the FCN1 gene (allele G = OR: 1.47; 95% CI: 1.02-2.12; p value: 0.041) [11], and Vander Cruyssen et al. found statistically significant associations with the rs2989727 variants (genotype GG = OR: 2.24; 95% CI: 1.45-2.12; p value: 0.041) and rs1071583 (genotype AA = OR: 1.94; 95% CI: 1.25-3.00) [13], as the protein encoded by this gene is mainly present in neutrophils and bone marrow [18, 19]. This evidence concerns the gene FCN1 and rheumatoid arthritis.