FISH ANALYSIS, MLL REARRANGEMENT
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.
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