Coduplication of the MLL and FLT3 genes in patients with acute myeloid leukemia

Tandem duplication (TD) of the MLL or FLT3 gene in acute myeloid leukemia ( AML) has been reported. We examined whether TD of these two genes occurs si multaneously. We analyzed 13 AML and 2 myelodysplastic syndrome patients, i ncluding 6 adult patients with trisomy 11 and 9 pediatric patients with TD of the FLT3 gene, using Rf-PCR followed by sequencing. Among these, TD of t he MLL and FLT3 genes was found in 5 and 10 patients, respectively. Notably , TD of both the MLL and FLT3 genes (coduplication) was detected in two AML patients, who died 6 and 14 months after diagnosis. TD of these two genes in AML is rare; thus, coduplication of these genes in the same patient is p redicted to be very rare. Although the mechanisms of TD of both genes are d ifferent, development of TD of both genes may be related to an unknown simi lar etiology in leukemia because the frequency of coduplication of these ge nes in a single patient is considered to be very low. Further studies of th e coduplication of these genes in AML patients may lead to the clarificatio n of its mechanism and clinical implications. (C) 2001 Wiley-Liss, Inc.