Double minutes (dmin) and homogeneously staining regions (hsr) in myeloid disorders: a new case suggesting that dmin form hsr in vivoReddy K.S.
Genzyme Genetics, New York, NY (USA)
We describe a case of an 87-year-old woman with myelodysplastic syndrome (MDS) in transformation. At presentation, the patient suffered from refractory anemia with excess of blasts (RAEB). The karyotype showed a clone with 3 to >20 double minutes (dmin) that were MYC-positive and, in addition, a cryptic deletion of MYC on one of the chromosome 8 homologs. The dmin varied both in size and in fluorescence intensity for the MYC probe following FISH. After six months, the disease had progressed to refractory anemia with excess of blasts in transformation (RAEBT). The corresponding karyotype showed a second cell line with two markers that appeared like rings and, again, a cryptic MYC deletion on one of the chromosome 8 homologs. The markers contained centromeres and amplified MYC sequences. The deletion of MYC on one of the chromosome 8 homologs and the variable sizes and intensities of the dmin supports an episome model for dmin formation. Chronologically, the MYC-positive dmin appeared first, followed by the appearance of MYC-positive marker chromosomes, suggesting that the dmin may have evolved to form homogeneously staining regions (hsr) in vivo.
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Manuscript received: 10 April 2007
Accepted in revised form for publication by A. Geurts van Kessel,: 4 June 2007.
Published online: December 14, 2007
Number of Print Pages : 7
Number of Figures : 4, Number of Tables : 1, Number of References : 38
Cytogenetic and Genome Research
Vol. 119, No. 1-2, Year 2007 (Cover Date: December 2007)
Journal Editor: Schmid, M. (Würzburg)
ISSN: 1424–8581 (print), 1424–859X (Online)
For additional information: http://www.karger.com/CGR