TP53I3 and Huntington disease: Widespread transcriptional alterations of the p53-signaling pathway in HD samples (Fig. 5a) included genes involved in cell-cycle arrest (Cyclin B1; Additional file 1: Figure S6b), apoptosis (TP53I3; Additional file 1: Figure S6c), and DNA repair (RRM2B; Additional file 1: Figure S6d).