TCF4 and Huntington disease: TCF4, a transcription factor involved in nervous system development, and SUZ12, a member of the polycomb repressive complex 2, were also enriched, suggesting roles for these complexes in repressing astrogliogenesis genes in HD (Figure 8D), that have also been implicated in HD neurons,39 endothelial genes in HD BMECs,6,40 and HD oligodendroglia.40