IL1A and rheumatoid arthritis: The most often studied SNPs of the IL-1 gene in RA are IL-1β (−511 C > T), IL-1β (3953 C > T), IL-1Ra (2018 C > T), IL-18 rs1946518 (−607 A > C), and IL-18 rs187238 (−137 G > C) (Table 1, Figure 2) [18,19,20,21,22,23,24,25].