The association of HLA-DRB1*0101 with disease susceptibility only becomes evident in the absence of the HLA-A*02 protective effect [2], whereas HLA-B*5401 is independently associated with susceptibility to disease; moreover, among patients with HAM/TSP, HLA-B*5401 is associated with a significant increase in PVL. This evidence concerns the gene HLA-B and tropical spastic paraparesis.