APP and Dravet syndrome: Even though the dysregulation of the SHH pathway and enhanced expression of the PTCH1 receptor in DS [209, 223, 252, 253] has been attributed, at least partially, to the triplication of APP [252], both SHH and PTCH1 are targets for transcriptional repression by PRC2 members [68, 236], and dysregulation of the SHH pathway can be caused by increased transcription of key pathway genes due to the increased dosage of HMGN1 and alleviation of PRC2 repression.