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IGH/FGFR3 t(4;14) by FISH

Test Code


Test Synonyms



Myeloma, monoclonal gammopathy (MGUS)


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

Reference Range

In a normal cell, a two orange and two green signal pattern is observed reflecting the two intact copies of the FGFR3 and IGH regions. In an abnormal cell, one orange (FGFR3), one green (IGH), and two fusion signal pattern (der (4) and der (14)) is observed.


The t(4;14) translocation is found in approximately 10% of myeloma patients and results in the deregulation of at least two genes, MMSET and fibroblast growth factor receptor 3 (FGFR3), with the formation of a fusion product between MMSET and the immunoglobulin heavy chain (IGH) locus and overexpression of FGFR3. In monoclonal gammopathy of undetermined significance (MGUS), a similar proportion of t(4;14) positive cases are found, but none of these express FGFR3. FISH can detect this translocation in either interphase or metaphase cells.

  1. Sibley et al. (2002). A molecular study of the t(4;14) in multiple myeloma. Br J Haematol. 118(2):514.