Susceptibility to HTLV-1 infection in children was linked to haplotypes IL6 −660G/−635C/−236G and IL10 −6653C/−1116G, independently of maternal provirus load and duration of breast-feeding, suggesting that host’s genetic variations, for both proinflammatory and anti-inflammatory cytokines genes, might be influencing the susceptibility to infection. The gene discussed is IL10; the disease is infection.