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IGH/MALT1 t(14;18) by FISH

Test Code

F IGH MALT1; FP IGH MALT1

Test Synonyms

t(14;18)(q32;q21), Immunoglobulin heavy chain / Mucosa associated lymphoid tissue lymphoma translocation gene 1

Associations

MALT lymphoma

Methodology

Fluorescence in situ Hybridization (FISH)

Turnaround Time

3-5 days

Specimen Requirements

F IGH MALT1
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

FP IGH MALT1
FFPE tissue is acceptable for FISH analysis. Preferred fixative is 10% neutral buffered formalin. Tissues preserved in B5 fixative or decalcified are usually not suitable for FISH. Tumor sections cut 3-5 µm thick and mounted on positively charged organosilane coated (silanized) slides work well. Request several unstained sections (two for each probe) and one H&E stained slide

 

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
FFPE Stable indefinitely when stored at 20°C to 25°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; Improper fixative

Reference Range

In a normal cell, a two orange, two green signal pattern is observed reflecting two intact copies of MALT1 and IGH, respectively. In an abnormal cell containing only the t(14;18)(q32;q21) translocation, a one orange, one green, and two fusion signal pattern is observed.

Description

Translocation (11;18)(q21;q21) has been associated with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). Translocation (11;18) leads to the fusion of the apoptosis inhibitor-2 (API2) gene and the MALT lymphoma-associated translocation (MALT1) gene. However, it has been found that 18% of MALT lymphomas have t(14;18)(q32;q21) or a translocation involving the IGH and MALT1 gene. MALT lymphomas with t(11;18)(q21;q21) usually do not have additional genetic aberrations, which is in contrast to t(14;18)(q32;q21) cases. Aneuploidy is seen in the majority of t(14;18)(q32;q21) MALT lymphomas. 
FISH can detect this rearrangement in either interphase or metaphase cells.

References
  1. Bertoni F et al. (2006). Delving deeper into MALT lymphoma biology. J Clin Invest. 116(1):22.
  2. Cavalli F et al. (2001). MALT lymphomas. Hematology. (1):241.
  3. Streubel B et al. (2003). t(14;18)(q32;q21) involving IGH and MALT1 is a frequent chromosomal aberration in MALT lymphoma. Blood. 101(6):2335.
  4. Cook JR. (2003). T(14;18)(q32;q21) involving MALT1 and IGH genes in an extranodal diffuse large B-cell lymphoma. Hum Pathol. 34(11):1212.