TCR signaling via p-AKT was reduced, albeit to a lesser degree, also in PD-1− CD4 and CD8 T cells from patients compared to HD (Fig. 2a), and could not be rescued by in vitro pembrolizumab, suggesting a role for other immune checkpoints in the regulation of TCR signaling in these T cell subsets. This evidence concerns the gene AKT1 and Huntington disease.