Fig. 1. Mouse models of Hsa21 trisomy. Hsa21 (purple) is syntenic with regions of mouse chromosomes 16 (Mmu16, blue), 17 (Mmu17, orange) and 10 (Mmu10, green). The positions of some Hsa21 genes implicated in the pathogenesis of DS and mentioned in this text are shown on the human chromosome. The transchromosomic Tc1 model carries a freely segregating copy of Hsa21 and is trisomic for the majority of genes on Hsa21[33]. Several mouse models are syntenic with a proportion of genes on Hsa21 and are segmentally trisomic for regions of Mmu16, such as the Dp1Yu[18], Ts65Dn[25], Ts2Cje[23], Ts1Cje[24], and Ts1Rhr[19] models. The Ts1Yah mouse model[22] is syntenic to Mmu17 and is trisomic for the sub-telomeric region of Hsa21.