PTPN22 and autoimmune thrombocytopenic purpura: Moreover, some studies had also shown that PTPN22 SNP1858 C > T and PTPN22 SNP1123 C > G have important role in human with ITP, which also shows that polymorphism in the PTPN22 gene may play a key role in genetic susceptibility and disease progression of ITP in children (Anis et al., 2011).