Meanwhile, the total amount of HTLV-1 tax mRNA in PBMCs and mRNA expression level in HTLV-1-infected cells (mRNA/DNA ratio) were significantly higher in HAM/TSP patients than in ACs and correlated with PVL, Tax-specific CTL frequency, and disease severity of the patients (81). The gene discussed is CNTN2; the disease is tropical spastic paraparesis.