argenx - Congenital Myasthenic Syndromes Sponsored Testing Program

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What is the argenx congenital myasthenic syndromes sponsored testing program?

The congenital myasthenic syndromes (CMS) testing program provides access to sponsored, no-charge genetic testing for individuals suspected to have CMS.

Through this program, individuals suspected of having CMS can access genetic testing to help bring them one step closer to a diagnosis and appropriate clinical management.

  • CMS are very rare with an estimated prevalence of ~2 per 1,000,000 people worldwide1-5
  • Symptoms that may raise suspicion of CMS and warrant genetic testing include muscle weakness and fatigability (weakness that typically worsens with activity) involving ocular, bulbar, facial, axial, limb, or respiratory muscles6-9
  • These symptoms are often present from birth or early childhood6-8
  • However, CMS presentation, severity, and disease course are highly heterogeneous and dependent on the underlying genetic defect6
  • It is important to pursue genetic testing in a timely manner to confirm a diagnosis of CMS, which allows for more tailored medical management and treatment options6,9,10
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Clinical features that raise suspicion of CMS

History

  • Patients or parents may report: Easy and/or varying fatigability, fluctuating or permanent muscle weakness, double vision, or respiratory insufficiency6-9
  • Symptoms typically present at birth or in the first 2 years of life, but manifestations up until later adulthood are possible6-9

Blood tests

  • Serum creatine kinase (CK) concentration typically normal or only slightly elevated6-8
  • Anti-AChR, anti-MuSK, and anti-LPR4 autoantibodies are not typically present. However, a lack of autoantibodies does not exclude seronegative myastenia gravis (MG)6-8

Electrophysiology

  • Repetitive nerve stimulation (RNS) reveals a decremental response and/or abnormal (increased) jitter or blocking may be seen on single fiber EMG (SFEMG)6-9
  • Nerve conduction studies are typically normal6-9

Clinical exam

  • Strength testing reveals fatigable muscle weakness, while the remainder of the neurological examination is typically normal6-8

Muscle biopsy and imaging

  • Typically normal6-8

Test options

This program offers testing with the following panels. Learn more about the panels in our test catalog before placing your order on this program page.

How to order

Our panels align with professional guidelines, making your potential next steps clearer.

  • Step 1 duotone icon

    Step 1

    Discuss testing and get consent from the eligible patient. Place your order via our online portal.

  • Step 2 duotone icon

    Step 2

    Collect your patient’s specimen using an Invitae collection kit and return it. Use the label provided to ship most samples at no additional charge from the US and Canada.

  • Genetic testing expert - Invitae icon

    Step 3

    Receive results online and access resources to inform your discussion with the patient about their results.

See how it works

Next steps and additional services

CMS masters of disguise

Genetic counseling services

Individuals in the US tested through the argenx CMS sponsored testing program are eligible for post-test genetic counseling to help them understand their test results. This service is made available at no charge as part of the program. Patients can access genetic counseling by scheduling a session through their patient portal or by contacting Invitae Client Services at 1-800-436-3037 and asking to schedule a genetic counseling appointment.

About argenx
argenx mission is to transform the lives of patients by translating immunology breakthroughs into novel antibody-based medicine.

  1. Ohno K, et al. J Hum Genet. 2025
  2. Krenn M, et al. J Neurol. 2023;270(2):909–16
  3. Smeets N, et al. Pediatr Neurol. 2024;158:57–65
  4. Mihaylova V, et al. J Neurol Neurosurg Psychiatry. 2010;81(9):973–7
  5. Natera-de Benito D, et al. Neuromuscul Disord. 2017;27(12):1087–98
  6. Finsterer J. Orphanet J Rare Dis. 2019;14(1):57
  7. Abicht A, et al. GeneReviews. https://www.ncbi.nlm.nih.gov/books/NBK1168/. May 9, 2003 (updated Dec 23, 2021). Accessed May 13, 2026
  8. Maggi L, et al. Neurol Sci. 2019;40(3):457–68
  9. Iyadurai SJP. Congenital Myasthenia Syndrome Treatment. Practical Neurology. July 19, 2021. Accessed April 24, 2026
  10. Muñoz-García MI, et al. J Clin Med. 2023;12(9):3308

    MED-US-a119-2600050 V1 07/2026

    Disclaimer: This is a sponsored testing program. While third parties and commercial organizations may provide financial support for this program, tests and services are performed by Labcorp Genetics. Healthcare professionals must confirm that patients meet certain criteria to use the program. Third parties and commercial organizations may receive de-identified (pseudonymized) patient data from this program, but at no time would they receive patient identifiable information. Third parties and commercial organizations may receive contact information for healthcare professionals who use this program. Genetic testing and counseling are available in the US. Healthcare professionals and patients who participate in this program have no obligation to recommend, purchase, order, prescribe, promote, administer, use or support any other products or services from Labcorp Genetics or from third parties or commercial organizations.