These citrulline PTM proteins elicit vigorous B and T cell autoimmune responses in both human T1D and NOD murine disease, including glutamic acid decarboxylase 65 (GAD 65), 78-kDa glucose-regulated protein (GRP78) (also called BiP, HSP5a), islet antigen-2 (IA2), islet-specific glucose 6 phosphatase catalytic subunit-related protein (IGRP), islet amyloid polypeptide (IAPP) and glucokinase (10). Here, PTPRN is linked to type 1 diabetes mellitus.