Higher levels of MMP-2 and MMP-9 were detected in the CSF and in infiltrating perivascular mononuclear cells in active lesions in the CNS, indicating that MMP-2 and MMP-9 may play a key role in the BBB breakdown in HAM/TSP patients (Umehara et al., 1998). This evidence concerns the gene MMP9 and tropical spastic paraparesis.