CD4 and tropical spastic paraparesis: To further validate our GWAS findings, we tested unique as well as shared genes between Japanese and Brazilian cohorts for differential expression in three independent transcriptomic data sets: HAM CD4 cells (the main HTLV-1 reservoir) from Japanese HAM patients 25, HAM whole blood from an Afro-Caribbean UK cohort26, and our own samples from the US HOST cohort27 (with >15 years follow-up).