To clarify the intrinsic factors involved in the manifestation of adult T-cell leukemidlymphoma (ATL) in Japan, a third nation-wide study on ATL was conducted by the Tand B-cell Malignancy Study Group. General clinico-epidemiological findings on ATL and infectious modes of transmission of human 1-lymphotropic virus type I (HTLV-I) from 181 ATL patients and their relatives were analyzed and the frequency of HLA antigens in 64 ATL patients was compared with that of 48 relatives of ATL probands, 340 controls from all Japan and 236 controls from Kyushu (Tanaka et a/., 1984). General findings on ATL were mostly the same as those in the 2 previous nation-wide studies. The age-specific positivity rate of anti-HTLV-I antibody in siblings of ATL patients was markedly higher than that in children of ATL patients. This suggests that there is a high risk of mothers of ATL patients transmitting HTLV-I to their children who may develop clinical ATL after reaching ATL risk age. Frequencies of HLA antigens A26 and 839, among patients with ATL in ATL-endemic areas (Kyushu and South Shikoku), were higher (RR>2.0 and p < 0.05) than those of controls in Kyushu, and lower (RR < 0.5 and p<O.O5) with respect to A24, Bw46, Bw52, Bw61 and DR7. The frequency of Bw52 was also lower in relatives positive for anti-HTLV-l antibody than in relatives without antibody. However, these differences were not statistically significant after correction for the 45 antigens typed. These results can neither support nor refute the possibility of genetic susceptibility to HTLV-I infection and manifestation of ATL. *The authors of this study are listed at the end. This group comprised: (1) members of the Lymphoma Study Group (Chairman: M. Shimoyama, Chief, Hematology-Oncology and Clinical Cancer Chemotherapy Division, National Cancer Center Hospital), which is one of the subgroups in "Studies of multidisciplinary treatment of cancer" (Chairman: K. Suemasu, Deputy Director, National Cancer Center Hospital), Grant Number 59s-1; and (2) other workers studying immunologic and serologic markers of lymphoid malignancies who were requested to participate in the present study.
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