Detection of a major gene predisposing to human T lymphotropic virus type I infection in children among an endemic population of African origin.

Human T lymphotropic virus type I (HTLV-I) is a human oncoretrovirus that causes an adult T cell leukemia/lymphoma and a chronic neuromyelopathy. To investigate whether familial aggregation of HTLV-I infection (as determined by specific seropositive status) could be explained in part by genetic factors, we conducted a large genetic epidemiological survey in an HTLV-I-endemic population of African origin from French Guiana. All of the families in 2 villages were included, representing 83 pedigrees with 1638 subjects, of whom 165 (10.1%) were HTLV-I seropositive. The results of segregation analysis are consistent with the presence of a dominant major gene predisposing to HTLV-I infection, in addition to the expected familial correlations (mother-offspring, spouse-spouse) due to the virus transmission routes. Under this genetic model, approximately 1. 5% of the population is predicted to be highly predisposed to HTLV-I infection, and almost all seropositive children <10 years of age are genetic cases, whereas most HTLV-I seropositive adults are sporadic cases.