FISH ANALYSIS, CHROMOSOME 7 ENUMERATION
Pseudonyms: Chromosome 7 loss, Deletion 7q, Monosomy 7, Myelodysplastic syndrome, MDS, t-MDS, Acute Myeloid Leukemia, AML, t-AML
TURNAROUND TIME: 7 to 10 days
Fluorescence in situ hybridization (FISH) Analysis
- 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 deletion of chromosome 7q or loss of chromosome 7 observed in some patients with myelodysplastic syndrome and AML; for diagnostic specimens, it is recommended that test be performed with chromosome analysis.
Methods: A dual-color FISH analysis performed on interphase nuclei using probes for the D7S486 and D75522 loci (7q31) and the ELN gene (7q11.23) which can detect deletions or duplications of the long arm of chromosome 7 and loss or gain of chromosome 7; analysis of 200 interphase cells; analysis of 500 interphase cells for minimal residual disease assessment.
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 MDS or AML with an abnormality of chromosome 7. 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:
- Patients with MDS or AML; establishing the percentage of neoplastic cells at diagnosis
- Identifying patients with MDS or AML with an abnormality of chromosome 7
- Monitoring the chromosome 7 abnormality during treatment