Several polymorphisms in the IL23R gene are strongly associated with the incidence and susceptibility to organ-characteristic autoimmune diseases, such as inflammatory bowel disease (IBD) [9], rheumatoid arthritis (RA) [10], psoriasis [11], and multiple sclerosis (MS) [12], but not with systemic autoimmune diseases such as systemic sclerosis (SSc) [7, 13], and systemic lupus erythematosus (SLE) [14, 15]. Here, IL23R is linked to rheumatoid arthritis.