POLR2A and Huntington disease: Similar to 24 hpi, Huntington's disease pathway was significantly enriched at 96 hpi with three upregulated genes (creb3l1, dnah3, and ENSCAFG00000011707) and four downregulated genes (apaf1, itpr1, polr2a, and lc25a4), among which apoptotic protease activating factor 1 (APAF1) is a key molecule in the intrinsic and mitochondrial pathway of apoptosis (Shakeri et al., 2017).