CALB2 and Dravet syndrome: As COUP-TFII+ progenitors are an important source of CR interneurons in mice (Xu et al., 2004), the decreased generation of COUP-TFII+ progenitors from Ts21 iPSCs and the reduced expression of COUP-TFII/NR2F in DS fetal brain provide a potential mechanism for the decreased population of CR+ interneurons in DS.