From each of Idd5.2 [11], Idd9.2 [12], Idd9.3 [12], Idd10 [10], Idd13 [13] and Idd18 [14] we chose immune-associated functional candidate genes to study in human type 1 diabetes: Nramp1/Slc11a1 from Idd5.2 [11]; Frap1 from Idd9.2 (unpublished); 4-1bb/Cd137/Tnfrsf9 from Idd9.3 [12] (unpublished); Cd101/Igsf2 from Idd10 [10]; B2m from Idd13 [15] and Vav3 from Idd18 (note that very recent congenic strain mapping results indicate that the Idd18 interval contains only one gene with known immunological function, namely the VAV3 gene, and this will be published elsewhere). The gene discussed is CD101; the disease is type 1 diabetes mellitus.