We observed a significant increase in ex vivo levels (%) of Fas+ lymphocyte in AC (1.8-fold) as well as in HAM/TSP patients (2.1-fold), when compared to HC (Kruskal–Wallis, Dunn’s posttest, p < 0.05, p < 0.001, respectively, Figure 2A). This evidence concerns the gene FAS and tropical spastic paraparesis.