CMT Advanced Evaluation – Demyelinating

Test Code

Test Details

Test code: 4007
Type of disorder: Peripheral Neuropathy, Hereditary
Disease(s) tested for: Charcot-Marie-Tooth Disease (CMT)
Genes Included: DNM2, EGR2, FGD4, FIG4, GDAP1, GJB1, LITAF, MPZ, MTMR2, NDRG1, PMP22, PRX, SBF2, SH3TC2, YARS
Tests included:
Informed Consent Required: This test requires physician attestation that patient consent has been received
Special Notes: If PMP22 Duplication/Deletion test is positive then additional tests are not performed (CPT: 81324). If PMP22 Duplication/Deletion Test is negative then the GJB1 (CX32) Deletion Test and the sequencing of the remaining genes in the panel will be performed at an additional charge (CPT code: Use 81448 only).

Technical Information

Clinical Significance: Detects duplications/deletions in PMP22 and deletions in Cx32 and sequence variations in Cx32, PMP22, MPZ, EGR2, LITAF, PRX, GDAP1, DNM2, YARS, SH3TC2, MTMR2, NDRG1, FGD4, FIG4, SBF2

Typical Presentation: Symmetric, slowly progressive distal sensory and motor polyneuropathy of the arms and legs resulting in muscle weakness and atrophy of the hands and feet. Foot deformities are common. Family history may or may not be present.
Methodology: Next Generation Sequencing, Multiplex Ligation-dependent Probe Amplification (MLPA)
Reference Range: No duplications/deletions detected, no sequence variation detected.

CPT Coding

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

CPT: No Reflex: 81324(1) only.  Reflex: 81448(1) only

Specimen Requirements

Please label each specimen tube with two forms of patient identification. These forms of identification must also appear on the requisition form.

Specimen Type: Whole blood
Specimen Stability: Room temperature: 10 days, Refrigerated: 10 days, Frozen: Unacceptable
Specimen Requirements: 8 mL (6 mL minimum) whole blood collected in two (lavender-top) EDTA tubes. Pediatric (0-3 years): 2 mL (1 mL minimum)
Instructions: Higher blood volumes ensure adequate DNA quantity, which varies with WBC, specimen condition, and need for confirmatory testing. Patients, 0-3 years have higher WBC, yielding more DNA per mL of blood

Shipping Considerations

Transport Temperature: Room temperature
Set-up/Analytic Time: 21-28 days

Additional Resources

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