HLA-B and tropical spastic paraparesis: Similarly, HLA-B*54, which is associated with a significantly increased risk of HAM/TSP (OR = 3.11, p = 0.0009), had a weakened impact on disease risk in the absence of KIR2DL2 (OR = 1.70, p = 0.2) but an enhanced impact in the presence of KIR2DL2 (OR = 12.05, p = 0.004).