The association of HT with T1DM has been examined at a molecular level with the description of an HLA class II peptide-binding pocket (DRβ-Tyr26, DRβ-Leu67, DRβ-Gln70, DRβ-Lys71 and DRβ-Arg74) that is strongly associated with this particular disease cluster, and demonstration that the pocket can bind peptides derived from thyroglobulin, TPO and glutamic acid decarboxylase 65 (a key autoantigen in T1DM) and cause T cell activation [46]. Here, TPO is linked to hematocrit.