The functional (R620W) variant of human PTPN22 (protein tyrosine phosphatase non-receptor 22) gene has been implicated in the risk to several autoimmune disorders, including type 1 diabetes, Graves' disease, rheumatoid arthritis and systemic lupus erythematosus. In an association study of this single nucleotide polymorphism with celiac disease (CD), comparison of 262 young diagnosis patients and 214 adult controls from Spain showed a higher frequency of the minor allele in the CD group (9.7% vs 5.6% in controls; P = 0.018), suggestive of an increased genetic risk to the disease (odds ratio = 1.82; 95% confidence interval 1.1-3.0). These results support the role of PTPN22 as a general autoimmunity locus involved in tolerance induction in the thymus.