PTPRN and type 1 diabetes mellitus: A hallmark of T1D is the emergence of β-cells destructive autoantibodies against endogenous antigens, which include proinsulin (biosynthetic precursor of insulin), proinsulin C-A junction (connection of C-peptide and A chain of proinsulin), glutamic acid decarboxylase 65 (GAD65, tolerogenic vaccine for T1DM prevention), islet antigen 2 (IA-2) and zinc transporter 8 (ZnT8) [25–29].