Among these, particular attention is paid to the potential pathophysiological role played in autoimmune disorders, including T1D and APS3v, by the C1858T variant of the PTPN22 (protein tyrosine phosphatase N22) gene [6], which encodes for the R620W variant Lyp protein tyrosine phosphatase [6]. Here, PTPN22 is linked to type 1 diabetes mellitus.