ISL1 and Huntington disease: Our analysis supports Foxo1 as a possible direct regulator of Isl1 expression that is impacted in HD; there are Foxo1 responsive elements in the Isl1 locus87,and loss of Isl1 regulation of the canonical dSPN identity gene Nrg3 (Neuroregulin 3), other transcription factors (e.g., Onecut2, Pou6f2), chromatin regulators (e.g., Phf7, Zhx3), and the sumoylation modifier Pias188 (Fig. 5e and Supplementary Fig. 7d).