PTPN22 and type 1 diabetes mellitus: In addition, there is some evidence that LADA is associated with a genetic background that is different from T1DM and T2DM, with an attenuated influence of key T1DM-associated HLA haplotypes compared to T1DM and an increased presence of PTPN22, INS and SH2B3 polymorphisms, compared to T2DM (4).