Fish Analysis, Chromosome 20 Deletion

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Pseudonyms: Deletion 20q, Myelodysplastic syndrome, MDS, Acute Myeloid Leukemia, AML, Polycythemia Vera, PV

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.
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 deletion of chromosome 20q observed in some patients with myelodysplastic syndromes, AML and polycythemia vera; it is recommended that test be performed with chromosome analysis.

Related Tests: Chromosome Analysis, Bone Marrow

Methods: A dual-color FISH analysis performed on interphase nuclei using a probe for the D20S108 locus (20q12) which can detect deletions of the long arm of chromosome 20 and a control probe; 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, AML or PV with a deletion of chromosome 20q. 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 be used as an adjunct to other clinical and pathological information.
Indications for Use:
  • Patients with MDS, AML or PV; establishing the percentage of neoplastic cells at diagnosis
  • Identifying patients with MDS, AML or PV with a deletion of chromosome 20q
  • Monitoring the chromosome 20q deletion during treatment
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