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HelpTest ID: PCMSP Postmortem Inherited Congenital Myasthenia Syndrome Gene Panel, Tissue
Ordering Guidance
This test is intended for use when whole blood is not available, and formalin-fixed, paraffin-embedded (FFPE) tissue is the only available specimen. If whole blood is available, consider CMSP / Inherited Congenital Myasthenic Syndrome Gene Panel, Varies.
Targeted testing for familial variants (also called site-specific or known variants testing) is available for the genes on this panel. See FMTT / Familial Variant, Targeted Testing, Varies. To obtain more information about this testing option, call 800-533-1710.
Specimen Required
Specimen Type: Tissue block
Collection Instructions: Submit a formalin-fixed, paraffin-embedded tissue block
Additional Information: Testing will be attempted on blocks of any age but may be canceled if adequate DNA concentration cannot be obtained.
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing (Spanish) (T826)
-Informed Consent for Genetic Testing for Deceased Individuals (T782)
Useful For
Identifying variants within genes known to be associated with congenital myasthenic syndrome, allowing for predictive testing of at-risk family members
Providing a comprehensive postmortem genetic evaluation in the setting of a congenital myasthenic syndrome
Identifying a disease-causing variant in the decedent, which may assist with risk assessment and predictive testing of at-risk family members
Genetics Test Information
This test utilizes next-generation sequencing to detect single nucleotide variants and deletions-insertions (delins) in 28 genes associated with congenital myasthenic syndromes: AGRN, ALG14, ALG2, CHAT, CHRNA1, CHRNB1, CHRND, CHRNE, COL13A1, COLQ, DNM2, DOK7, DPAGT1, GAA, GFPT1, GMPPB, LAMB2, LRP4, MUSK, PLEC, PREPL, RAPSN, SCN4A, SLC18A3, SLC25A1, SLC5A7, SYT2, VAMP1. See Method Description for additional details.
Identification of a disease-causing variant may assist with diagnosis, prognosis, clinical management, recurrence risk assessment, familial screening, and genetic counseling for congenital myasthenic syndromes.
Method Name
Sequence Capture and Targeted Next-Generation Sequencing (NGS)
Reporting Name
Postmortem Myasthenia PanelSpecimen Type
VariesSpecimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Clinical Information
Congenital myasthenic syndromes occur as a result of compromised neuromuscular transmission. Clinical manifestations include fatigable weakness involving ocular, bulbar, and limb muscles. The severity and disease course are highly variable, but individuals usually present in infancy or early childhood. The clinical phenotype associated with a neonatal onset can include feeding difficulties, poor suck and cry, choking spells, eyelid ptosis, and muscle weakness. The clinical phenotype associated with a later childhood onset can include abnormal muscle fatigue, delayed motor milestones, ptosis, and extraocular muscle weakness.
The combination of the wide variability in symptoms and age of presentation can make congenital myasthenic syndromes hard to diagnosis. Given that congenital myasthenic syndromes are a heterogeneous group of disorders, multigene panels can be an efficient and cost-effective way to establish a molecular diagnosis for individuals. Postmortem diagnosis of a hereditary form of a congenital myasthenic syndrome may assist in confirmation of the cause of death, as well as risk assessment in living family members.(1-2)
Reference Values
An interpretive report will be provided.
Interpretation
All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(3) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.
Clinical Reference
1. Byring RF, Pihko H, Tsujino A, et al. Congenital myasthenic syndrome associated with episodic apnea and sudden infant death. Neuromuscul Disord. 2002;12(6):548-553. doi:10.1016/s0960-8966(01)00336-4
2. Imperatore V, Mencarelli MA, Fallerini C, et al. Potentially Treatable Disorder Diagnosed Post Mortem by Exome Analysis in a Boy with Respiratory Distress. Int J Mol Sci. 2016;17(3):306. Published 2016 Feb 27. doi:10.3390/ijms17030306
3. Richards S, Aziz N, Bale S, et al. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015;17(5):405-424
4. Lyadurai SJP. Congenital myasthenic syndromes. Neurol Clin. 2020;38(3):541-552
Day(s) Performed
Varies
Report Available
28 to 42 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81443
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PCMSP | Postmortem Myasthenia Panel | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 620639 | Test Description | 62364-5 |
| 620640 | Specimen | 31208-2 |
| 620641 | Source | 31208-2 |
| 620642 | Result Summary | 50397-9 |
| 620643 | Result | 82939-0 |
| 620644 | Interpretation | 69047-9 |
| 620645 | Additional Results | 82939-0 |
| 620646 | Resources | 99622-3 |
| 620647 | Additional Information | 48767-8 |
| 620648 | Method | 85069-3 |
| 620649 | Genes Analyzed | 82939-0 |
| 620650 | Disclaimer | 62364-5 |
| 620651 | Released By | 18771-6 |
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