Myotonic Syndrome Advanced Evaluation

Test Code

Test Details

Test code: 5506
Type of disorder: Neuromuscular Disorders
Disease(s) tested for: Myotonic Syndrome
Genes Included: ATP2A1, CAV3, CLCN1, CNBP, DMPK, HSPG2, SCN4A
Informed Consent Required: This test requires physician attestation that patient consent has been received

Technical Information

Clinical Significance: Detects sequence variations in 5 genes and repeat expansions in 2 genes known to cause myotonia.

Typical Presentation: Impaired ability to relax skeletal muscles following a contraction. Myotonias may be dystrophic (termed myotonic dystrophy).
Methodology: Next Generation Sequencing, Repeat Expansion Detection by PCR, Southern Blot
Reference Range: No mutations detected. DM1 (DMPK) normal: 5-34 CTG repeats. DM2 (CNBP) normal: Less than 177 base pairs

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: 81187(1), 81234(1), 81404(1), 81406(2), 81479(1)

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

Letters of Medical Necessity

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