Molecular Pathology Laboratory Network

F IGH MAF

t(14;16)(q32;q23), Immunoglobulin heavy chain / MAF gene

Myeloma, MGUS

Fluorescence in situ Hybridization (FISH)

88367 x2 - Morphometric analysis, in situ hybridization, automated
88368 x2 - Morphometric analysis, in situ hybridization, manual

3 days

• 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 in MPLN RPMI media
• 3.0 mL (min. 2.0 mL) FNA in MPLN RPMI media
• 10% neutral buffered formalin fixed paraffin embedded tissue

• 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

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

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

In a normal cell, a two orange, two green signal pattern will be observed. In an abnormal cell containing the t(14;18) translocation, a one orange (MAF), one green (IGH), and two fusion (IGH/MAF and MAF/IGH) signals observed.

The t(14;16)(q32;q23) is detectable in 2–10% of patients with plasma cell myeloma and in about 25% of myeloma cell lines. The t(14;16)(q32;q23) is difficult to detect by conventional karyotypes. Although some studies report a low prevalence of the t(14;16) in newly diagnosed patients, other studies reveal that a small percentage of patients show the t(14;16) at the time of initial diagnosis. Translocation (14;16)(q32;q23) has also been described in MGUS.
FISH can detect this rearrangement in either interphase or metaphase cells.