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Non-dystrophic myotonia (SCN4A gene)
Clinical Genetic Test
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offered by
Molecular Genetics and Cytogenetics, Clinical Laboratory Service
GTR Test Accession: Help GTR000593439.1
CAP
INHERITED DISEASEMUSCULOSKELETAL
Registered in GTR: 2021-08-02
View version history
Last annual review date for the lab: 2024-07-31 LinkOut
At a Glance
Test purpose: Help
Diagnosis; Mutation Confirmation
Conditions (1): Help
Batten-Turner congenital myopathy
Genes (1): Help
SCN4A (17q23.3)
Methods (1): Help
Molecular Genetics - Sequence analysis of select exons: Bi-directional Sanger Sequence Analysis
Target population: Help
Not provided
Clinical validity: Help
In Chilean patients with non-dystrophic myotonias, SCN4A variants were observed …
Clinical utility: Help
Establish or confirm diagnosis
Ordering Information
Offered by: Help
Molecular Genetics and Cytogenetics, Clinical Laboratory Service
View lab's website
Test short name: Help
SCN4A gene
Specimen Source: Help
  • Buccal swab
  • Isolated DNA
  • Peripheral (whole) blood
  • Saliva
Who can order: Help
  • Licensed Physician
Test Order Code: Help
2859
Lab contact: Help
Marcela Lagos, MD, Lab Director
[email protected]
+56 223548515
Contact Policy: Help
Laboratory can only accept contact from health care providers. Patients/families are encouraged to discuss genetic testing options with their health care provider.
Test service: Help
Clinical Testing/Confirmation of Mutations Identified Previously
Informed consent required: Help
Decline to answer
Pre-test genetic counseling required: Help
Decline to answer
Post-test genetic counseling required: Help
Decline to answer
Recommended fields not provided:
How to Order, Test strategy, Test development
Conditions Help
Total conditions: 1
Condition/Phenotype Identifier
Test Targets
Genes Help
Total genes: 1
Gene Associated Condition Germline or Somatic Allele (Lab-provided) Variant in NCBI
Methodology
Total methods: 1
Method Category Help
Test method Help
Instrument *
Sequence analysis of select exons
Bi-directional Sanger Sequence Analysis
* Instrument: Not provided
Clinical Information
Test purpose: Help
Diagnosis; Mutation Confirmation
Clinical validity: Help
In Chilean patients with non-dystrophic myotonias, SCN4A variants were observed 93% of patients, including 83% with myotonia permanens due to the Gly1306Glu variant. The high frequency of the Gly1306Glu variant in SCN4A in Chilean patients suggests a founder effect and expands its phenotypic spectrum.
View citations (1)
  • Avila-Smirnow D, Vargas Leal CP, Beytía Reyes MLA, Cortés Zepeda R, Escobar RG, Kleinsteuber Saa K, Lagos Lucero M, Avaria Benapres MLA, Padilla Pérez O, Casar Leturia JC, Mellado Sagredo C, Sternberg D. Non-dystrophic myotonia Chilean cohort with predominance of the SCN4A Gly1306Glu variant. Neuromuscul Disord. 2020;30(7):554-561. doi:10.1016/j.nmd.2020.04.006. Epub 2020 May 19. PMID: 32593548.
Clinical utility: Help
Establish or confirm diagnosis
View citations (1)
  • Avila-Smirnow D, Vargas Leal CP, Beytía Reyes MLA, Cortés Zepeda R, Escobar RG, Kleinsteuber Saa K, Lagos Lucero M, Avaria Benapres MLA, Padilla Pérez O, Casar Leturia JC, Mellado Sagredo C, Sternberg D. Non-dystrophic myotonia Chilean cohort with predominance of the SCN4A Gly1306Glu variant. Neuromuscul Disord. 2020;30(7):554-561. doi:10.1016/j.nmd.2020.04.006. Epub 2020 May 19. PMID: 32593548.

Variant Interpretation:
What is the protocol for interpreting a variation as a VUS? Help
ACMG-AMP guidelines for the interpretation of sequence variants, 2015 (PMID: 25741868).

Are family members with defined clinical status recruited to assess significance of VUS without charge? Help
Decline to answer.

Will the lab re-contact the ordering physician if variant interpretation changes? Help
Decline to answer.
Recommended fields not provided:
Target population, Is research allowed on the sample after clinical testing is complete?, Sample negative report, Sample positive report
Technical Information
Availability: Help
Tests performed
Entire test performed in-house
Analytical Validity: Help
For validation, exon 22 of SCN4A gene from 18 patients from eight unrelated families were studied, identifying the heterozygous variant c.3917G>A in 15 patients. Sequencing analysis approaches an analytical sensitivity of almost 100%. *Other variants in exon 22 can also be detected.
Proficiency testing (PT):
Is proficiency testing performed for this test? Help
Yes

Method used for proficiency testing: Help
Formal PT program

PT Provider: Help
American College of Medical Genetics / College of American Pathologists, ACMG/CAP
Recommended fields not provided:
Test Confirmation, Assay limitations, Description of internal test validation method, Citations for Analytical validity, Description of PT method, Major CAP category, CAP category, CAP test list
Regulatory Approval
FDA Review: Help
Not provided
Additional Information

IMPORTANT NOTE: NIH does not independently verify information submitted to GTR; it relies on submitters to provide information that is accurate and not misleading. NIH makes no endorsements of tests or laboratories listed in GTR. GTR is not a substitute for medical advice. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.