IFNG and tropical spastic paraparesis: Infiltration of inflammatory cells and the presence of plaques, especially in the thoracic spinal, a spontaneous proliferation of T lymphocytes, increase in inflammatory cytokines such as IL‐2, IL‐4, IL‐6, IL‐15, TNF‐α, IL‐1β, and IFN‐γ has been observed in the serum and cerebrospinal fluid of HAM/TSP patients (Fuzii et al., 2014; Shoeibi et al., 2013).