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EGR1 5q deletion, monosomy 5 by FISH

Test Code

F EGR1

Test Synonyms

5q-, -5/del(5)(q31), deletion 5q31

Associations

5q- syndrome, Myelodysplasia (MDS), Myeloproliferative disease (MPD), Acute myelogenous leukemia (AML);
Lenolidomide

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
Blood and bone marrow = 4°C to 25°C, specimens are stable up to 72 hours
Fixed cell pellets are stable for years when stored at -28°C to 15°C
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

Description

An interstitial deletion of chromosome 5, del(5q), is associated with MDS/MPD and AML. Involvement of chromosome 5 is found in 40% of therapy-related myeloid disorders, whereas it is found in only 5–7% of de novo AML. Deletions of the long arm of chromosome 5 could vary considerably, and involvement of all bands between 5q11 and 5q33~q34 have been identified. The frequent loss of 5q suggests that important tumor suppressor genes map to this genomic segment. Previous studies have indicated that a critical tumor suppressor gene for AML and more aggressive forms of MDS is located in 5q31. A distinct common deletion region for the 5q2 syndrome was localized to 5q32. However, most patients with a 5q2 syndrome or AML and MDS with del(5q) have large deletions. Monosomy 5 usually appears as part of a complex karyotype involving several other chromosomes and rarely as a sole abnormality. Monosomy 5 has been considered less likely to be a primary karyotypic abnormality. FISH can detect these abnormalities in either interphase or metaphase cells.

The so-called “5q- syndrome” associated with isolated deletion of chromosome 5 in MDS is a favorable prognostic indicator. In contrast, complex karyotypes with deletion of chromosome 5 in MDS are associated with an adverse outcome. Deletion of 5q or monosomy 5 in AML, with or without other chromosome changes, is also associated with a poor prognosis. Other chromosome changes commonly occurring with 5q- are monosomy 7/7q-, trisomy 8, and 20q-. These changes can be detected by using individual FISH probes or as part of the MDS probe panel.

FISH for abnormalities of chromosome 5 can be performed on interphase or metaphase cells.

References
  1. Anderson C et al. (2002). Cancer Genetics and Cytogenetics. 136:101–107.
  2. Royer-Pokora B et al. (2006). Cancer Genetics and Cytogenetics. 167:66–69.