HLA-B and type 1 diabetes mellitus: Work in T1D identified a microsatellite D6S2223 4.9kb telomeric of DQ in the extended class I region, as being associated with a reduction in the risk conferred by the DR3 extended haplotype on disease [50], with further work narrowing the association to a region encompassing the class III and HLA-B/-C gene regions [51].