Test Code

F D20

Test Synonyms

20q-, deletion 20q12

Associations

Acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), myeloproliferative disorder (MPD)

Methodology

Fluorescence in situ Hybridization (FISH)

Turnaround Time

3-5 days

Specimen Requirements

5mL peripheral blood in sodium heparin
3mL bone marrow in sodium heparin
Fixed cytogenetically prepared cells in sterile centrifuge tube with pellet visible in 3:1, Methanol:Acetic Acid

Specimen Stability

Storage & Handling

4°C to 25°C during transit, but specimens may be transported on refrigerated gel packs. Do not allow the gel pack to come in contact with the specimen. Do not freeze. Extreme temperatures should be avoided.

Causes for Rejection

Clotted specimen; Specimen exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells

Reference Range

In a normal cell, the expected pattern is the two orange signal pattern. In an abnormal cell containing the deletion, the one orange signal pattern is observed.

Description

Deletions of the long arm of chromosome 20 represent a common chromosomal abnormality associated with myeloid disorders, in particular with myeloproliferative disorders (MPD), myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). The deletion is rarely seen in lymphoid malignancies. Other chromosome changes commonly occurring with deletion 20q are monosomy 5/5q-, monosomy 7/7q-, and trisomy 8. FISH can detect this abnormality in either interphase or metaphase cells.

References

1. Brezinova Jana et al. (2005). Cancer Genetics and Cytogenetics. 160:188–192.
2. Bilhou-Nabera C. (2000). del(20q) in myeloid malignancies. Atlas Genet Cytogenet Oncol Haematol.
3. Wang PW et al. (1998). Refinement of the commonly deleted segments in myeloid leukemias with del(20q). Gene Chromosomes Cancer. 21(2):75.