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Neuromuscular diseases

Congenital myasthenic syndromes (CMS)

A group of inherited diseases present from birth in which the muscles tire quickly. Signals do not pass well from nerve to muscle. Drooping eyelids, difficulty swallowing and difficulty breathing can occur.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

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This page is translated from the Turkish original.

This disease is followed through the “Neuromuscular diseases” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

The signal is not passed on well at the point where nerve and muscle meet. As a result, the muscles are weak and tire quickly. A change in one of more than 35 genes can cause this. Unlike myasthenia caused by the immune system, it is inherited.

Which symptoms can occur?

Symptoms usually begin shortly after birth or in early childhood. Severity ranges from very mild to severe.

  • Drooping eyelids and limited eye movements
  • Difficulty chewing, swallowing and speaking
  • Weakness in the arms and legs that tires quickly
  • Feeding difficulties in infancy
  • Short pauses in breathing (in some babies)
  • Delay in crawling and walking
  • Episodes that get worse with fever, infection or tiredness
  • Stiff joints present from birth (in severe cases)

How is it diagnosed?

The diagnosis is suspected from a history of weakness since early childhood and the examination. A nerve-muscle test called EMG and blood antibody tests are done. The subtype is found with a genetic test. This is important, because a treatment that helps one type can make another type worse.

Treatment and care

Treatment is chosen according to the subtype. Medicines that improve signal transmission from nerve to muscle are often used. But not every medicine is suitable for every type. Physiotherapy, nutritional and breathing support may be needed. Fever and infection can trigger episodes; this is why close follow-up is important. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

It is usually passed on through recessive inheritance. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. Recessive diseases can be more common when relatives marry each other. Rarely, it is passed on through dominant inheritance; then a single changed gene is enough. Genetic counselling clarifies the family's risk.

Source: MedlinePlus Genetics: Congenital myasthenic syndrome · NORD: Congenital Myasthenic Syndromes

Key facts

How common is it?
Prevalence: 1-9 per 1 000 000 (Europe)
When does it usually start?
Infancy, Newborn period

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

For all rare diseases: Nadir Hastalıklar Federasyonu

Links checked on October 8, 2026.

Guides related to this disease

  • Home care and medical devices · Home health service, oxygen and respiratory device reports, wheelchairs and orthoses, power outage notification, emergency plan.

Support and help

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about Congenital myasthenia

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

  • Could this trial be suitable for us?
  • If we take part, how would current treatment and check-ups be affected?
  • Where does the trial take place, and how are travel and accommodation handled?
  • What happens if we want to leave the trial?

ClinicalTrials.gov lists 4 active interventional studies for this disease. 1 is recruiting now; none has a site in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

See all studies on ClinicalTrials.gov · Joining clinical trials

Neuromuscular diseases: other news

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:590 · ICD-11 8C61

Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.

The information on these pages is for general information only and does not replace medical advice. Talk to your doctor about diagnosis and treatment decisions. In an emergency in Türkiye, call 112.

Every update is based on an open source and labeled with its level of evidence. No advertising and no drug brand names. Our scientific principles

This page was translated from Turkish by the Doktorclub editorial team.