FISH ANALYSIS, CHROMOSOME 16 INVERSION or TRANSLOCATION
Pseudonyms: inv(16), t(16;16), CBFB Rearrangement, Acute Myeloid Leukemia, AML
TURNAROUND TIME: 7 to 10 days
TESTING METHODOLOGY: Fluorescence in situ hybridization
- Collect: 2 mL bone marrow aspirate in sodium heparin (green); 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 the inversion of chromosome 16 or the 16;16 translocation characteristic of AML with marked eosinophilia but also observed in AML without eosinophilia and in t-AML; it is recommended that test be performed with chromosome analysis.
Methods: A dual-color FISH analysis performed on interphase cells using a break-apart probe for the CBFB gene on chromosome 16q22 which can detect the inv(16)(p13q22) and t(16;16); analysis of 200 interphase cells; analysis of 500 interphase cells for minimal residual disease assessment.
Interpretation: A positive result (inversion 16 or 16;16 translocation) 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 AML with a rearrangement involving the CBFB gene. A negative result indicates no CBFB rearrangement 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 be used as an adjunct to other clinical and pathological information.
Indications for Use:
- Patients with AML; establishing the percentage of neoplastic cells at diagnosis.
- Identifying patients with AML with an inversion of chromosome 16 or a 16;16 translocation involving the CBFB gene.
- Monitoring the CBFB rearrangement during treatment.