We have identified multiple HLA alleles associated with HAM/TSP—HLA-B*07:02, HLA-C*07:02, HLA-DQB1*05:01, and HLA-DRB1*01:01—as risk alleles and HLA-B*40:06, HLA-DQB1*06:02, and HLA-DRB1*15:01 as alleles showing a protective effect. The gene discussed is HLA-DQB1; the disease is tropical spastic paraparesis.