Some reports showed PD-1 expression is upregulated in both infected T cells and CTL (Yasuma et al. 2016b; Enose-Akahata et al. 2019) and these PD-1+ cells in CD8+ T cells showed CTL dysfunction in HAM/TSP patients (Manuel et al. 2013). The gene discussed is CD8A; the disease is tropical spastic paraparesis.