Familial adult T-cell leukemia.

Two siblings who developed adult T-cell leukemia (ATL) are presented. The patient and 7 of 26 healthy family members examined had the serum antibodies against ATL-associated antigens (ATLA). This family study shows that two main routes of transmission of human T-cell leukemia virus (HTLV) may be involved: one is the route from parents to children and the other is horizontal transmission among spouses, especially from husband to wife; the anti-ATLA-positive family is considered to be a high-risk group for ATL.