Chromosome observations of acute promyelocytic leukemia treated with all-trans retinoic acid.

Chromosome changes were observed in 8 patients with acute promyelocytic leukemia during the all-trans retinoic acid-induced differentiation course. Karyotype of patient bone marrow specimens after short-term incubation were analyzed using Giemsa-R banding. Analyses showed all 8 patients had the abnormal translocation between chromosomes 15 and 17, but when those patients were treated with all-trans retinoic acid and were in remission, the characteristic t(15;17) chromosomal abnormality disappeared. However, this aberration of chromosomes detected in 3 patients persisted during the early period of RA induction, although the patients could still achieve complete remission. However, it was found that the percentage of abnormal karyotypes declined during this early period. This phenomenon may be an important indicator for clinical remission. When one case relapsed, the t(15;17) reappeared. Thus the chromosome t(15;17) was not only useful in diagnosis, but also helpful in observing prognosis in acute promyelocytic leukemia.