PTPN22 and autoimmune disease: In view of the discrepant data regarding the association between the protein tyrosine phosphatase non-receptor 22 (PTPN22) rs2476601 (R620W, 1858C→T) polymorphism and susceptibility to autoimmune diseases including inflammatory bowel diseases (IBD), we investigated whether this functional single-nucleotide polymorphism influences IBD risk in a group of Moroccan patients.