SIBLING ADULT T-CELL LEUKEMIA-LYMPHOMA AND CLUSTERING OF HUMAN T-CELLLYMPHOTROPIC VIRUS TYPE-I INFECTION IN A JAMAICAN FAMILY

Background. Human T-cell lymphotropic virus type I (HTLV-I) infection is endemic in jamaica, with an estimated crude seroprevalence of 5%. A dult T-cell lymphoma/leukemia (ATL), a disease caused hy HTLV-I, has a n incidence of 1-2/100,000 in the Jamaican population. Familial ATL ha s not previously been reported from Jamaica. Methods. Hospital records and histologic specimens of the two cases were reviewed. HTLV-I infec tion was confirmed by antibody testing and by polymerase chain reactio n on paraffin-embedded tissue, where serum was unavailable. Family mem bers were identified by the patients' parents. After giving informed c onsent, family members were asked to complete an interviewer-administe red questionnaire and to agree to phlebotomy. Results. ATL developed 1 0 years apart in two siblings from a Jamaican family at age 16 and 24 years. A study of 19 members of their extended family, including both parents, 2 grandparents, and 3 siblings, revealed an overall HTLV-I se roprevalence of 17%. This compared with 75% among parents and siblings living in the same household as the patients. HTLV-I antibody-positiv e (HTLV-I-positive) and negative family members had similar mean age. Three of 3 HTLV-I-positive subjects were breast-fed, compared with 10 of 15 HTLV-I-negative subjects. Intravenous drug abuse, sex with prost itutes, homosexuality, and blood transfusion were not reported. The me an number of sexual partners were similar. Both parents, who were anti body-positive, had polylobated atypical lymphocytes in their periphera l blood. Conclusion. The HTLV-I antibody seroprevalence is greater in the family than in the general population, consistent with the modes o f transmission. The antibody seronegativity of both grandmothers sugge sts sexual transmission between parents. The development of ATL at age 16 and 24 years is consistent with maternal-infant transmission and a long latent period, as reported by other authors.