Test Overview
Test Methodology

Reverse transcription followed by Polymerase Chain Reaction (PCR) with detection by capillary electrophoresis.

Test Usage

Rhabdomyosarcoma is a member of the group of "small round blue cell" tumors, and must be distinguished from morphologically similar pediatric tumors. Rhabdomyosarcoma includes two major histological subtypes, embryonal and alveolar. Of these, the alveolar type is associated with a worse prognosis. Two recurrent and distinctive chromosomal translocations occur in alveolar rhabdomyosarcoma. The t(2;13)(q35;q14) translocation joins the PAX3 and FOXO1 (FKHR) genes in approximately 60% of alveolar rhabdomyosarcomas, while the less common t(1;13)(p36;q14) joins PAX7 with FOXO1 in approximately 20% of cases. The juxtaposed genes lead to expression of chimeric transcripts consisting of the 5’ portion of PAX3 or PAX7 fused to the 3’ portion of the FOXO1 gene. This test qualitatively detects the PAX3/FOXO1 and PAX7/FOXO1 fusion transcripts in fresh/frozen or formalin-fixed paraffin embedded tissues. Testing can aid in distinguishing alveolar rhabdomyosarcoma from other similar tumors.

Reference Range *

Interpretive report provided. The specific fusion transcript type is reported with a positive test result.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

This assay is expected to be positive in approximately 80% of all alveolar rhabdomyosarcomas. Approximately 20% of tumors diagnosed as alveolar rhabdomyosarcoma based on histologic grounds have been found to be negative for a PAX/FOXO1 translocation or fusion transcript.

Test Details
Days Set Up
Monday - Thursday
Analytic Time

2 - 7 days

Soft Order Code
MiChart Code
PAX/FOXO1 Translocation (Alveolar Rhabdomyosarcoma) by PCR
  • PAX3 Chimeric Transcript Detection
  • PAX7 Chimeric Transcript Detection
  • FKHR Chimeric Transcript Detection
  • PAX/FKHR Alveolar Rhabdomyosarcoma Translocation Assay
  • ARMS
  • Alveolar Rhabdomyosarcoma Translocation Detection
Molecular Diagnostics
Molecular Diagnostics
Specimen Requirements
Collection Instructions

A formalin-fixed, paraffin-embedded tissue block containing an area with a high percentage of neoplastic cells (for micro-/macro-dissection) is preferred. Unstained, UNBAKED slides (5-8, 10-micron slides; 10-15 if few neoplastic cells are present) with associated H&E stained slide are also acceptable. Decalcified tissue or other fixatives will be accepted and the assay attempted, however these may result in failed testing due to degraded nucleic acid. Both blocks and slides should be stored at room temperature.

Alternate Specimen
Previously extracted RNA may also be accepted.
Normal Volume
Formalin-fixed, paraffin-embedded tissue. Extracted RNA is also acceptable if extracted in a CLIA certified laboratory.
Additional Information

By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes pathologist interpretation of results billed as a separate additional charge. This test is not available without interpretation.

CPT Code
81401 x2
Fee Code
NA079, NA080
Pro Fee CPT
NY State Approved