Early Onset Myotonia Evaluation

Test Code
207
Orders for this test for patients residing in New York state cannot be accepted at this time.

Test Details


Test code:207
Type of disorder:Neuromuscular Disorders
Disease(s) tested for:Myotonic Dystrophy, Type 1, Myotonia Congenita, Sodium Channel Myotonia
Genes Included: DMPK, CLCN1, SCN4A,
Tests included:CLCN1 DNA Sequencing Test
DMPK DNA Test (DM1)
SCN4A (Myotonia) DNA Sequencing Test
Informed Consent Required:This test requires physician attestation that patient consent has been received

Technical Information


Clinical Significance:

Detects CTG repeat expansions in the DMPK gene, and point mutations in the CLCN1 and SCN4A gene

Typical Presentation: Adults may present with myotonia, ptosis and muscle wasting. Other symptoms may include frontal balding, cataracts, cardiac complications, infants may present with severe hypotonia, skeletal deformities, developmental delay and mental retardation.

Indications for testing: Proximal and/or distal stiffness or weakness. Non-dystrophic, non-syndromic myotonia with mild hypertrophy. Dystrophic but non-syndromic myotonia for differential.

 

Methodology: Next Generation Sequencing, Repeat Expansion Detection by PCR, Long Read Sequencing
Reference Range:No sequence variants detected for CLCN1 and SCN4A genes. DM1 (DMPK) normal: 5-34 CTG repeats

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:81234(1), 81406(2)

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,
Instructions:Higher blood volumes ensure adequate DNA quantity, which varies with WBC, specimen condition, and need for confirmatory testing.

Shipping Considerations


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

Additional Resources

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