Fig. 1.

Pairwise deletion of redundant ultraconserved elements in the locus of the mouse Arx gene [4] (a, b) and redundant strongly conserved enhancers of the mouse Gli3 gene [8] (c). A combined deletion of two dorsal forebrain enhancers hs122 and hs123 leads to a smaller dentate gyrus (white staining) with disorganized appearance (a). A combined deletion of two ventral forebrain enhancers hs119 and hs121 leads to a drastic decrease in the density of striatal cholinergic neuron density (b). A combined deletion of two Gli3 limb enhancers in a sensitized genetic background leads to a severe polydactyly (c). ChAT choline acetyltransferase, UCE ultraconserved element