IFNG and tropical spastic paraparesis: IFN-γ, an important proinflammatory cytokine, is commonly associated with the pathogenesis of HAM [75,76,77] and among asymptomatic individuals, the polymorphic allele for the IFNG +874A/T polymorphism was associated with higher levels of IFN-γ and proviral load, and a more constant follow-up was suggested for these patients to detect possible infection-related symptoms [54].