Fish Analysis, MLL Rearrangement

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Pseudonyms: Chromosome 11 translocation; 11q23; Acute Myeloid Leukemia; AML; t-AML; Pediatric Acute Lymphocytic Leukemia; Pediatric ALL; Adult Acute Lymphocytic Leukemia; Adult ALL

TURNAROUND TIME: 7 to10 days
TESTING METHODOLOGY: Fluorescence in situ hybridization
  • Collect: 2 mL bone marrow aspirate in sodium heparin (green) for children and adults; 5 mL peripheral blood in sodium heparin (green) also acceptable.
  • Minimum Collection: 1 mL bone marrow or 2 mL peripheral blood
  • Transport: bone marrow or peripheral blood in sodium heparin (green) at 20-25°C; specimen should arrive in the laboratory within 24 hours of collection.
  • Stability: Ambient: 24 hours; Refrigerated: 24 hours; Frozen: unacceptable
  • Unacceptable Conditions: Frozen or clotted specimens; paraffin-embedded specimens; specimens in anticoagulants other than sodium heparin.
A Cytogenetics Laboratory Test Requisition must accompany the specimen. Contact the Cytogenetics Laboratory at 918-502-1722 to obtain further information.
Test Summary: Test can detect rearrangements of the MLL gene which occur in acute myeloid leukemias and acute lymphocytic leukemias
Methods: A dual-color break-apart FISH analysis performed on interphase cells using two probes for the MLL gene on chromosome 11q23; analysis of 200 interphase cells for diagnostic specimens and 500 interphase cells for minimal residual disease.
Test Limitations: Rearrangements of the MLL gene may involve many different chromosomal partners. When an MLL rearrangement is identified, reflex testing is needed to identify the translocation partner.
Interpretation: A positive result is reported when the percent of cells with an abnormality exceeds the normal reference range for the probes. The detection of an abnormal clone indicates a diagnosis of AML or ALL with a MLL rearrangement. A negative result indicates no abnormality was observed but does not rule out the presence of a neoplastic disorder.
FDA Approval: This test is not approved by the FDA and it should used as an adjunct to other clinical and pathological information.
Indications for Use:
  • Identifying patients with rearrangements of the MLL gene on chromosome 11
  • Monitoring the MLL rearrangement during treatment
  • Detecting residual disease in patients with MLL rearrangements