Data from the current study extend that of previous work identifying that CTLA-4, the IL2_21 region, 6q23 (TNFAIP3), SH2B3, PRKCQ, MMEL1 and now TAGAP are susceptibility loci that are common to the three autoimmune diseases examined in the current study: T1D, CeD and RA [2,5]. The gene discussed is CTLA4; the disease is type 1 diabetes mellitus.