The first report of familial adult T-cell leukaemia lymphoma in the United Kingdom.

We describe two siblings who developed adult T-cell leukaemia lymphoma (ATLL) within 4 years. Both were black of Afro-Caribbean extraction, but one had been born in the United Kingdom and had visited the Caribbean only once. Both patients were HTLV-1 seropositive, as was their mother; their father and brother were negative. The older sibling had the lymphoma form of ATLL, whilst the younger had chronic ATLL. The former was unresponsive to chemotherapy and died of progressive disease; the latter experienced transient responses to various treatments and is alive 5 years after presentation. Immunophenotyping showed a CD4+, CD25+ phenotype; Southern blot demonstrated a monoclonal integration of HTLV-I in the tissues involved. This report, of the first familial ATLL in the U.K., supports the suggestion of transmission of HTLV-I from mother to child and documents the development of ATLL in second-generation Caribbean immigrants.