Clinical characteristics of infant acute leukemia with or without 11q23 translocations.

Of 34 infants less than 1 year of age with acute leukemia, 20 had an 11q23 translocation (group I), 8 had t(4;11), 5 had t(11;19), 3 had t(1;11), 2 had t(10;11), 1 had t(9;11), and the other had an 11q+ chromosome. Nine had other chromosome changes (group II), including t(1;19), t(8;14), 5q- chromosome, or +8 in one each, and a translocation involving 7p22 in two. The other five had normal diploidy in their leukemic cells (group III). Thus, the 11q23 translocation was seen in 50% of the leukemic infants, and in as high as 75% of the infants less than 6 months old. While the 7p22 translocations were both seen in those less than 6 months, the four chromosome abnormalities without 11q23 translocation mentioned above and normal diploidy were found only in those 6 months old or more. The group I patients had higher leukocyte counts than the group II (p less than 0.05) or group III (p less than 0.01) patients. Of the 20 group I patients, 16 were classified as having ALL, and 4 were classified as having ANLL. Eleven of 15 ALLs with the 11q23 translocation showed an Ia+, CALLA-, and B4+ (8 of 9 examined) immunophenotype. Coexpression of lymphoid and myeloid Ags was seen in four ALLs and two ANLLs with the 11q23 translocation. The survival of group II patients (median, 9 months) was significantly shorter than that of group I (median, 19 months) (p less than 0.05) or group III (median, 44 months) (p less than 0.01) patients; the difference in the survival between group I and group III patients was not significant. It is noteworthy that 5 of the 20 group I patients have survived 20 months or more without relapsing.