PTPN2 and type 1 diabetes mellitus: To determine whether the IL2RArs2104286 risk haplotype and the PTPN2rs1893217 risk alleles together could explain the reduced response to IL-2 in T1D and MS patients relative to control subjects, we held the genotype at IL2RA and PTPN2 constant for the protective alleles and compared responses in disease patients to age and ethnicity matched controls (Figure 6A and B).