To determine if the rescue of abnormal morphologies observed in HD patient iPSC-neurons (Q53 & Q66) with PIAS1 hetKO translates to mouse cortical neurons, we carried out a short-term Pias1 KD in mouse primary neuronal cultures derived from E18 BACHD cortical neurons on EM grids and visualized cells with cryoET (Fig. 8c, d). The gene discussed is PIAS1; the disease is Huntington disease.