By contrast, DRB1-GB-7-Pro was protective against the onset of HAM/TSP and was shared by multiple HLA alleles, including HLA-DRB1*15:01 and other, less frequent DRB1 alleles, such as DRB1*15:02, DRB1*15:06, DRB1*15:61, and DRB1*16:02 (Table 3 and SI Appendix, Table S2). Here, HLA-DRB1 is linked to tropical spastic paraparesis.