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AML1-ETO translocation (8,21) by FISH

F AML

Test Synonym:

AML1-ETO t(8;21)

CPT Code:

88367 x2 - Morphometric analysis

Turnaround Time:

3 days

Methodology:

Fluorescence in situ hybridization (FISH)

Specimen Requirements:

  • 5.0ml (min. 3.0 ml) peripheral bloodin sodium heparin preferred, EDTA accepted
  • 3.0ml (min 1.0ml) bone marrow in sodium heparin preferred, EDTA accepted
  • 5mm3 fresh tissue in MPLN RPMI media
  • 3.0ml (min 2.0ml) FNA in MPLN RPMI  media

    • Causes for Rejection:

    Clotted specimen; specimen exposed to extreme temperature; anticoagulant toxic to cells; insufficient number of cells


    Specimen Stability:

  • Peripheral blood and bone marrow stable at 18-25°C for 72 hours
  • Fresh tissue or FNA at 2°-8°C stable for 72 hours

    • Storage and Handling:

    Whole blood and bone marrow ship ambient

    Fresh tissue or FNA ship in a styrofoam container with an ice pack (do not allow ice pack to directly contact sample)

    Reference Range:

    2> FISH results indicate whether rearrangement is present or absent

    Indication:

    Translocation between the long arm of chromosome 8 and the long arm of chromosome 21 is one of the most common translocations in acute myeloid leukemia (AML) of both children and adults.  The t(8;21)(q22;q22) occurs in about 12% of AML cases, including 40-50% of  the FAB-M2 subtype.  The translocation results in the fusion of the AML1 gene at 21q22 with the ETO locus at 8q22 to create a novel chimeric AML1/ETO gene on the derivative chromosome 8.  The t(8;21) is typically associated with a favorable prognosis in adults, the prognosis in children is poor with only a 30% long term remission rate.

    The AML1-ETO Dual Color FISH assay is used to detect rearrangements between 8q22 and 21q22.  In a normal cell, two orange and two green signals will be detected to signify the presence of two normal copies of chromosomes 8 and 21.  In a cell with the t(8;21), two fusion (yellow or orange/green) signal will be seen representing the two rearranged chromosomes.  One orange and one green signal will also be visualized to indicate the presence of one normal 8 and one normal 21.  The AML1-ETO probe assay can be performed on interphase cells or metaphase spreads. 

    References:

    1. Huret JL . t(8;21)(q22;q22). Atlas Genet Cytogenet Oncol Haematol. September 1997.
      URL : http://www.infobiogen.fr/services/chromcancer/Anomalies/t0821.html
    2. Xaio Z, et al. (2001). Molecular characterization of genomic AML1-ETO fusions in childhood leukemia. Leukemia 15:1906.
    3. Yan M, et al. (2004). Deletion of an AML1-ETO C-terminal Ncor/SMRT-interacing region strongly induces leukemia development. PNAS 101(49):17186.
    4. Tonks A. et al. (2004). Expression of AML1-ETO in human myelomonocytic cells selectively inhibits granulocytic differentiation and promotes their self-renewal. Leukemia 18(7):1238.