Myeloma, monoclonal gammopathy (MGUS)
Fluorescence in situ Hybridization (FISH)
2.0 mL (min. 1.0 mL) peripheral blood in sodium heparin preferred, EDTA accepted
1.0 mL (min. 0.5 mL) bone marrow in sodium heparin preferred, EDTA accepted
5 mm^3 fresh tissue or 3.0 mL (min. 2.0 mL) FNA in MPLN RPMI media
Whole blood and bone marrow, ship ambient
Fresh tissue or FNA ship in a Styrofoam container with a cool/refrigerated pack (Do not allow cool pack to directly contact sample)
Clotted specimen; Specimen exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells
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.