DSCAM and Dravet syndrome: Dosage sensitivity of the effects of DSCAM in DS is supported by the ability of Dscam loss of function mutations to correct the disrupted dendritic fasciculation of a subset of retinal ganglion cells in the Ts65Dn mouse model of DS (which has three copies of a chromosomal segment orthologous to a HSA21 segment that contains DSCAM) (Blank et al., 2011).