PTPN22 and type 1 diabetes mellitus: Equality of risk conferred by the C-C haplotype in comparison to the C-T haplotype at rs2476601-rs12566340 was also observed (Table 4; OR = 1.01 [0.94–1.09], P = 0.78), consistent with the absence of common allelic heterogeneity at PTPN22 in T1D.