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Congenital Myasthenic Syndrome via the COLQ Gene

Summary and Pricing

Test Method

Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
6997 COLQ 81479 81479,81479 $640 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
6997COLQ81479 81479(x2) $640 Order Options and Pricing

Pricing Comments

This test is also offered via our exome backbone with CNV detection (click here). The exome-based test may be higher priced, but permits reflex to the entire exome or to any other set of clinically relevant genes.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Turnaround Time

18 days on average for standard orders or 13 days on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Angela Gruber, PhD

Clinical Features and Genetics

Clinical Features

Congenital myasthenic syndromes (CMS) are disorders of the neuromuscular junction resulting from abnormalities of presynaptic, synaptic, or postsynaptic proteins. CMS are characterized by fatigable weakness affecting limb, ocular, facial, and bulbar muscles. Neonates present with feeding problems, choking, feeble cry, and muscle weakness. Patients presenting in later childhood are seen with abnormal exercise-induced fatigue and difficulty running. Most patients present prior to 2 years of age although rare exceptions are reported (eg. Croxen et al. Neurol 59:162-168, 2002). Symptoms are extremely variable and are in some case induced by febrile illness, infection, or excitement (eg. Byring et al. Neuromuscul Disord 12:548-553, 2002). Life-threatening respiratory crises may occur in affected neonates or older children. CMS may be differentiated from myasthenia gravis, an acquired autoimmune disorder, by earlier age of onset and by negative serology tests for anti-acetylcholine receptor (AchR) and anti-Musk antibodies. CMS with acetylcholinesterase (AChE) deficiency at the synaptic basal lamina has traditionally been differentiated from other forms of CMS clinically by its severe, early-onset phenotype, and pathophysiologically by absence of AChE at the end plate. However, a cohort of end plate acetylcholinesterase deficient patients was recently described with mild clinical presentations similar to those observed in patients with familial limb-girdle CMS in which weakness is primarily found in proximal muscles (Mihaylova et al. Brain 131:747-759, 2008; Müller et al. Neuropediatrics 35:183-189, 2004). Patients with AChE deficiency have been found to be responsive to ephedrine (Mihaylova et al. 2008).

Genetics

Abnormalities of proteins involved with neuromuscular transmission underlie CMS, limb girdle CMS, Pena-Shokeir syndrome, and multiple pterygium syndromes. These disorders, which may represent a phenotypic continuum of a single entity, are most often inherited in an autosomal recessive manner. Synaptic CMS with acetylcholinesterase deficiency (OMIM 603034) is inherited as an autosomal recessive condition secondary to variants in the COLQ gene (OMIM 603033). Truncating (Ohno et al Proc Natl Acad Sci USA 95:9654-9659, 1998), splice site (Schreiner et al. Neuromusc Disord 17:262-265, 2007), and missense (Müller et al. 2004) variants have been reported. Evidence exists for reduced expression of disease in heterozygous carriers of COLQ variants (Schreiner et al. 2007).

The collagenic tail of the end plate acetylcholinesterase is encoded by exons 1 – 17 of the COLQ gene located on chr 3p25.

Clinical Sensitivity - Sequencing with CNV PG-Select

Sensitivity for CMS testing is at least 50% overall; 30% for CHRNE, 10% for RAPSN, and 7.5% for COLQ (GeneReviews, Abicht and Lochmüller, 2006).

Testing Strategy

This test provides full coverage of all coding exons of the COLQ gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

A comprehensive diagnostic algorithm can be found in (GeneReviews, Abicht and Lochmüller, 2006). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in COLQ.

Gene

Official Gene Symbol OMIM ID
COLQ 603033
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Endplate Acetylcholinesterase Deficiency AR 603034

Related Test

Name
Fetal Akinesia Deformation Sequence (FADS)/Lethal Multiple Pterygium Syndrome Panel

Citations

  • Angela Abicht, Hanns Lochmuller (2006). "Congenital Myasthenic Syndromes."
  • Byring RF, Pihko H, Tsujino A, Shen XM, Gustafsson B, Hackman P, Ohno K, Engel AG, Udd B. 2002. Congenital myasthenic syndrome associated with episodic apnea and sudden infant death. Neuromuscul Disord 12: 548-553. PubMed ID: 12117478
  • Croxen R, Hatton C, Shelley C, Brydson M, Chauplannaz G, Oosterhuis H, Vincent A, Newsom-Davis J, Colquhoun D, Beeson D. 2002. Recessive inheritance and variable penetrance of slow-channel congenital myasthenic syndromes. Neurology 59: 162-168. PubMed ID: 12141316
  • Mihaylova, V., et.al. (2008). "Clinical and molecular genetic findings in COLQ-mutant congenital myasthenic syndromes." Brain 131(Pt 3): 747-59. PubMed ID: 18180250
  • M├╝ller et al. (2004). Synaptic congenital myasthenic syndrome in three patients due to a novel missense mutation (T441A) of the COLQ gene. Neuropediatrics 35:183-189. PubMed ID: 15248101
  • Muller, J. S., et.al. (2004). "The congenital myasthenic syndrome mutation RAPSN N88K derives from an ancient Indo-European founder." J Med Genet 41(8): e104. PubMed ID: 15286164
  • Ohno, K., et.al. (1998). "Human endplate acetylcholinesterase deficiency caused by mutations in the collagen-like tail subunit (ColQ) of the asymmetric enzyme." Proc Natl Acad Sci U S A 95(16): 9654-9. PubMed ID: 9689136
  • Schreiner et al. Neuromusc┬áDisord 17:262-265, 2007 PubMed ID: 17300939

Ordering/Specimens

Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page


Specimen Types

Specimen Requirements and Shipping Details

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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