Recent genome-wide association studies have provided convincing evidence that the chromosomal 4q27 region harboring the IL-2 and IL-21 genes is associated with chronic inflammatory disorders, including coeliac disease (a gluten-sensitive enteropathy), psoriasis, diabetes, rheumatoid arthritis, inflammatory bowel disease (IBD), asthma, and systemic lupus erythematosus (SLE) [31–33]. Here, IL21 is linked to rheumatoid arthritis.