However, since CD4 or CD8 Tscm represent only a minor subset of Fas+ lymphocytes (46), a Tscm origin of Fashi cells is not likely, considering the two-step increase we observed both ex vivo and in vitro (Figures 2A,B and 4A), first in AC and second in HAM/TSP. The gene discussed is FAS; the disease is tropical spastic paraparesis.