TANDEM DUPLICATION OF THE MLL GENE IN MYELODYSPLASTIC SYNDROME-DERIVED OVERT LEUKEMIA WITH TRISOMY-11

Trisomy 11 as a sole chromosomal abnormality is a rare aberration obse rved in myelodysplastic syndrome (MDS) or acute myeloblastic leukemia (AML). Recently a partial tandem duplication of the MLL gene, located on chromosome band 11q23, has been identified in de novo AML with tris omy 11, We describe a 72-year-old woman suffering from MDS-derived ove rt leukemia with trisomy 11 and a tandem duplication of the MLL gene, At first the patient was found to have myeloblasts with Auer rods in t he peripheral blood and diagnosed as MDS, refractory anemia with exces s of blasts in transformation (RAEB-T), After 2 months a picture of ov ert leukemia (AML; M2) developed as shown by an increased number of my eloblasts. Various chemotherapy regimens had little effect, and she di ed of disease progression 15 months after admission. During her clinic al course, the chromosome analyses consistently showed 47,XX, +11. Sou thern blot analysis of leukemic blasts on admission and in accelerated phase revealed identical rearranged bands of the MLL gene. Fluorescen ce in situ hybridization analysis excluded the possibility of masked t ranslocation of the MLL gene to other chromosomes. Reverse transcripta se-polymerase chain reaction (RT-PCR) analysis using a forward exon 6 primer and a backward exon 3 primer demonstrated an in-frame fusion of exon 8 with exon 2. Our results indicated that a partial tandem dupli cation of exons 2-8 of the MLL gene could be observed in MDS-derived o vert leukemia as well as de novo AML with trisomy 11. (C) 1997 Wiley-L iss, Inc.