Test Directory

• IGH, 14q32.3
• MAF, 16q23

The t(14;16) is generated during B-cell maturation in germinal centers possibly as a result of errors in the immunoglobulin heavy chain (IGH) switch recombination (Bergsagel et al, 2001). The anomaly appears to be an early event in the genesis of plasma cell neoplasms (PCN) as it occurs in both monoclonal gammopathy of unknown significance (MGUS) and multiple myeloma (MM). 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. The most common additional abnormalities in these series are -13/13q-, amplification of 1q, trisomy or tetrasomy of chromosome 15 and structural (mostly deletions of the short arm in the region 8p21.3) and numerical of chromosome 8. 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. The cases with t(14;16) are resistant to bortezomib therapy. FISH can detect this rearrangement in either interphase or metaphase cells.

• Lithium heparin is not acceptable.
• Specimens must be collected in a sterile collection container.

Each specimen must be accompanied by a requisition form, script, electronic order or physician note. Each order must indicate the reason for testing (diagnosis).

• Transport to the laboratory at room temperature.
• Store specimen as whole blood, in original tube, at room temperature and deliver to lab within 24 hours.
• If specimen cannot be delivered within 24 hours, store in refrigerator. Do not freeze specimen.
• Specimens collected on the weekends must be refrigerated upon arrival at HNL Lab Medicine.

• Specimen frozen
• Specimen arriving without any form of patient identification (unlabeled)
• Specimen with attached needles
• Specimen arriving with broken or leaking collection tube
• Unfixed specimen treated with fixative

In a normal cell, the expected signal pattern is two orange signals and two green signals. In an abnormal cell containing a typical translocation, the expected signal pattern is one orange signal, one green signal, and two fused signals.

• FISH Translocation IGH/MAF
• t(14;16)