A follow up study confirmed PTPN22 R620W association in case-control and family T1D cohorts and provided the first evidence that PTPN22 was a general autoimmune risk locus by demonstrating strong association in 901 UK Caucasian GD and 833 ethnically matched controls (P=10-4, OR=1.43) [69]. Here, PTPN22 is linked to type 1 diabetes mellitus.