It has been suggested that the percentage of Foxp3+ Tregs in CD4+CD25+ cells in HTLV-I carriers and healthy controls is higher than this percentage in patients with HAM/TSP (78, 80); while in HTLV-I carriers the percentage of Foxp3+ cells in the CD4+ population is lower than this percentage in patients with HAM/TSP (81-83). This evidence concerns the gene IL2RA and tropical spastic paraparesis.