Down's syndrome and acute myelofibrosis. Time study of DNA content during the progression to leukemia.

Flow cytometry (FCM) for the determination of cellular DNA content was performed on multiple bone marrow biopsy specimens from a 3-year-old boy with Down's syndrome and myelofibrosis. A rapidly fatal acute nonlymphocytic leukemia developed within 3 months after initial bone marrow evaluation. The clinical and morphologic changes corresponded to the development of aneuploidy as determined by FCM and cytogenetic analysis. These findings support the clinical observations of the premalignant potential of myelofibrosis in Down's syndrome.