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MALT1 18q21 rearrangement by FISH

Test Code

F MALT; FP MALT

Test Synonyms

18q21, t(11;18)(q21;q21), MALT lymphoma-associated translocation 1 gene

Associations

Mucosa-associated lymphoid tissue (MALT lymphoma)

Methodology

Fluorescence in situ Hybridization (FISH)

Turnaround Time

3-5 days

Specimen Requirements

F MALT
2.0 mL (min. 1.0 mL) peripheral blood in sodium heparin, EDTA accepted
1.0 mL (min. 0.5 mL) bone marrow in sodium heparin, EDTA accepted
5 mm^3 fresh tissue or 3.0 mL (min. 2.0 mL) FNA in MPLN RPMI media

FP MALT
10% neutral buffered formalin fixed paraffin embedded tissue

Specimen Stability
Peripheral blood and bone marrow stable at 18-25°C for 72 hours
Fresh tissue or FNA stable at 2-8°C for 72 hours
FFPE stable stable indefinitely
Storage & Handling

Whole blood and bone marrow, ship ambient
Fresh tissue, FNA or paraffin embedded tissue, ship in a Styrofoam container with a cool/refrigerated pack (Do not allow cool pack to directly contact sample)

Causes for Rejection

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

Reference Range

A normal cell will show two fusion (yellow or orange/green fused) signals representing two intact copies of 18q21. A cell with a rearrangement involving the MALT1 gene will show a fusion signal on the normal chromosome 18 along with one orange and one green signal indicating disruption of the MALT1 gene on the rearranged chromosome.

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 most often seen in the majority of t(14;18)(q32;q21) MALT lymphomas.  >br>
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. 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.
  3. 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.
  4. Cavalli F et al. (2001). MALT lymphomas. Hematology.(1):241.