To confirm whether the in vivo expression profiles of menin and bach2 mRNA were related to the clinical status of HTLV-1 infection, the expression levels of menin and bach2 mRNA in PBMCs from HTLV-1 infected individuals and normal uninfected controls (NCs) were examined by qRT-PCR in 21 patients with ATL (acute-type, n = 12; lymphoma-type, n = 6; smoldering-type, n = 2; chronic-type, n = 1) and 13 patients with HAM/TSP, 11 ACs, and 11 NCs. Here, BACH2 is linked to tropical spastic paraparesis.