BACE2 and Dravet syndrome: However, to explore how trisomy 21 affects ENS development, a recent study evaluated the ENS in two DS mouse models, namely, Ts65Dn and Tc1, which are trisomic for many chromosomes 21 homologous genes, including Dscam and Bace2. Both Ts65Dn and Tc1 mice have markedly reduced submucosal plexus neuron number; however, normalizing the copy number of Dscam does not rescue the defect.