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New type of leukemia identified
Edward R. Winstead


Researchers have proposed that children with a particular defect on chromosome 11 have a unique type of leukemia not previously recognized. They identified the new disease by profiling the expression of thousands of genes in several dozen leukemia patients. Those with the chromosome-11 defect had a unique gene expression profile. Doctors have known for years that these children have severe relapses after chemotherapy, and the microarray data may ultimately lead to more effective treatments.

Stanley J. Korsmeyer, of the Dana-Farber Cancer Institute in Boston, led the study. Children with the chromosome-11 translocation, which occurs when part of the chromosome breaks off and migrates to a new location in the genome, showed a distinct expression pattern. Patients with this type of translocation have particularly poor prognoses and tend to relapse soon after chemotherapy.

"Our data strongly suggest a model in which a specific chromosomal translocation results in a distinct type of lymphoblastic leukemia," the researchers write in Nature Genetics. "To our knowledge, this is the first whole-genome profiling study to show that a chromosomal translocation can specify a unique gene expression program."

The researchers used 12,600-gene microarrays to distinguish the new disease, called mixed-lineage leukemia, from two other types of leukemias—acute lymphoblastic and acute myelogenous. Compared to the other two types, the new category is characterized by the underexpression of about 1,000 genes and the overexpression of about 200 genes.

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Armstrong, S. A. et al. MLL translocations specify a distinct gene expression profile that distinguishes a unique leukemia. Nat Genet. Published online December 2, 2001.

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