Several groups have identified CNVs in the context of ASD patients 158–162, although only a few have yet been modeled in hiPSCs. In particular it is interesting that de novo duplications of the 7q11.23 region is associated with ASD, whereas deletion of the same region causes Williams-Beuren syndrome, characterized increased sociability 163. Willliams syndrome has been modeled in hiPSC and it has been shown that Willliam syndrome progenitors have increased doubling time and apoptosis, while neurons show increased dendritic spines and synapses compared with typically developing neural cells 164 as well as prolonged repolarization times and a deficit in voltage-activated K+ currents 165.
