RÉSUMÉ
<p><b>OBJECTIVE</b>To investigate the association between trisomy 21 abnormalities and the clinical and cytogenetic features of hematologic malignancies.</p><p><b>METHODS</b>Chromosome preparations were made on bone marrow cells by using direct method and/or unstimulated short-term cultures. Karyotypes were analyzed by R-banding.</p><p><b>RESULTS</b>Thirteen patients (1.5%) with acute myeloid leukemia (AML) including 6 cases of M5b, 8 (2.2%) with acute lymphoblastic leukemia (ALL) and 4 cases with other hematologic malignancies had acquired trisomy 21, and in 13 patients it occurred as the sole cytogenetic abnormality. The remaining had combination with other abnormalities. The median survival for the 19 patients with trisomy 21 was 9 months.</p><p><b>CONCLUSION</b>M5b was the major type in AML with sole acquired trisomy 21.Trisomy 21 as the sole abnormality appeared to have a poor prognosis.</p>