Acquired chromosome rearrangements, including fine interstitial deletions, in a patient with Down syndrome and monoblastic leukemia.

A female child with Down syndrome who developed acute monoblastic leukemia is reported. Anemia associated with milk leukopenia was first recognized when the patient was 14 months old. Acute monoblastic leukemia was diagnosed 1 year later; cytogenetic studies were performed on circulating leukemic cells at this time. Analysis of elongated, finely banded chromosomes revealed three structural rearrangements, including two rather subtle interstitial deletions, in addition to trisomy 21 which was representative of the patient's constitutional karyotype. The karyotype of the leukemic cells was 47,XX,+21,t(3;18)(p23;q11.2), del(7)(q31.1q31.3), del(9)(p22p24 or p21p23). The patient received no cytostatic chemotherapy and died 4 months after the diagnosis of acute leukemia was made.