Test Directory

• IGH::FGFR3, t(4;14)
• MYC::IGH/8cen, t(8;11)
• IGH::MAF, t(14;16)
• IGH::MAFB, t(14;20)

FGFR3::IGH t(4;14) Translocation Probe

The fibroblast growth factor receptor 3 (FGFR3) translocation to the immunoglobulin heavy chain (IGH) is found in plasma cell leukemia, multiple myeloma, plasmacytoma and monoclonal gammopathy of unknown significance (MGUS). It represents the second more frequent IGH associated rearrangement, after t(11;14); and is detected by interphase FISH or RT-PCR in 25% MM cell lines, 15-20% primary MM and 0-10% MGUS lines. The t(4;14) is not karyotypically detectable and has an unfavorable prognosis, even in patients treated with high dose chemotherapy. Additional abnormalities are hypodiploid karyotype and -13 / 13q- in major part of cases.

There are two fusion genes generated as a result of the t(4;14). FGFR3 is brought under the influence of the Ig gene enhancer Ea on der(14) and MMSET under the influence of enhancer Eµ on der(4). Both FGFR3 and MMSET genes are deregulated by the translocation and a IGH-MMSET fusion transcript, detectable by RT-PCR, is generated. No IGH::FGFR3 fusion proteins are generated, but promoter exchange between both partner genes. Somatic mutations similar to what has been found in thanatophoric dwarfism have been identified in some cases; they may also contribute to abnormal FGFR3 activation.

MYC::IGH/8cen t(8;14) Translocation Probe

Cytogenetic studies using chromosome analysis and interphase fluorescence in situ hybridization (FISH) are routine procedures for prognostic stratification of plasma cell myeloma. Cytogenetic abnormalities are both numerical and structural and include trisomies, whole or partial chromosome deletions and gains and chromosomal translocations. About half of multiple myeloma tumors are hyperdiploid with 48 to 75 chromosomes and have gains of three or more of the odd-numbered chromosomes 3, 5, 7, 9, 11, 15, 19, and 21. The other half of multiple myeloma tumors are mostly non-hyperdiploid with <48 or >75 chromosomes and usually have an immunoglobulin heavy chain (IGH) translocation at chromosome 14q32 Common secondary cytogenetic abnormalities in MM include deletion of chromosome 13q (or monosomy 13) found in about 50%, deletion of chromosome 17p including TP53 (or monosomy 17) found in about 10%, deletion of 1p found in about 20% and duplication or amplification of 1q found in about 40% of MM. In addition, MYC locus translocations are also present in about 40% of multiple myeloma. These reposition MYC near a promiscuous array of PC specific super enhancers (including immunoglobulin heavy chain (IGH), immunoglobulin kappa locus (IGK), immunoglobulin lambda locus (IGL) and non-Ig enhancers) MYC translocations can contribute to progression from MGUS to multiple myeloma

Bone marrow samples used for plasma cell neoplasia testing are sorted for CD138 positive selection cells using magnetic beads. FISH analysis on the CD138 positive selected cells has been shown to increase diagnostic sensitivity.

IGH::MAF t(14;16)(q32;q23) Translocation Probe

The t(14;16) is generated during B-cell maturation in germinal centers possibly as a result of errors in the 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.

IGH::MAFB, t(14;20)(q32;q12) Translocation Probe

Plasma cell myeloma (PCM) is a complex and genetically heterogenous hematological malignancy involving clonal proliferation of plasma cells in bone marrow. Standard karyotype and fluorescence in situ hybridization (FISH) evaluation of bone marrow is required in the initial diagnostic workup to risk stratify patients based on their cytogenetic status. Primary cytogenetic events are classified as either hyperdiploid or non-hyperdiploid. Common in non-hyperdiploid cases is rearrangement of the IGH gene on chromosome 14q32.33, most commonly with the CCND1 gene at 11q13.3, and to a lesser extent FGFR3/MMSET genes at 4p16.3 or the MAF gene at 16q23.2. The rarest of these IGH translocations involves the MAFB gene at 20q12. Approximately 40-50% of myeloma cases demonstrate an IGH gene rearrangement. The t(14;20)(q32;q12) is the rarest of the five most common IGH-rearrangements, found in approximately 1% of cases [Manier et al, 2016].

Specimen Types: Leukemic Blood or Bone Marrow

Preferred Collection Container: Green Top (Sodium Heparin)

Alternate Collection Container: Lavendar Top (EDTA)

Desired Specimen Volume: 3 - 5 mL

Minimum Acceptable Volume: 1 mL

• 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

FGFR3::IGH, t(4;14) Translocation Probe

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.

MYC::IGH/8cen, t(8;14) Translocation Probe

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.

IGH::MAF, t(14;16)(q32;q23) Translocation Probe

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.

IGH::MAFB, t(14;20)(q32;q12) Translocation Probe

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 Multiple Myeloma Reflex Panel
• MM Reflex Panel