TYK2 and rheumatoid arthritis: For example, loci conferring risk for more than 1 autoimmune disease include the STAT4 locus for RA and SLE; the CD289-CTLA4 locus for T1DM and celiac disease or RA; the ICAM3 locus for RA with SLE; the TYK2 locus for RA with SLE, T1DM, and inflammatory bowel disease; and the RGS1 locus for T1DM and multiple sclerosis and celiac disease (14).