congenital myasthenic syndrome 3C

Congenital Myasthenic Syndrome 3C (CMS3C) Description

Congenital Myasthenic Syndrome 3C (CMS3C), also known as AChR deficiency, is a rare genetic disorder that affects the neuromuscular junction. It is characterized by early-onset muscle weakness with variable severity.

• Early-Onset Muscle Weakness: CMS3C typically presents at birth or shortly after, with symptoms ranging from mild to severe muscle weakness.
• Variable Severity: The severity of symptoms can vary greatly among individuals, from minor weakness to the inability to move.
• Autosomal Recessive Inheritance: CMS3C is inherited in an autosomal recessive pattern, meaning that a person must inherit two copies of the mutated gene (one from each parent) to develop the condition.

Key Features

• Low amplitude of miniature endplate potential and current
• Early-onset muscle weakness due to deficiency of acetylcholine receptors at the neuromuscular junction

References

• [1] Congenital myasthenic syndrome associated with AChR deficiency is a disorder of the postsynaptic neuromuscular junction (NMJ) clinically characterized by early-onset muscle weakness with variable severity. Electrophysiologic studies show low amplitude of the miniature endplate potential (MEPP) and current (MEPC) resulting from deficiency of AChR at the endplate. [1]
• [4] Congenital myasthenic syndrome associated with AChR deficiency is a disorder of the postsynaptic neuromuscular junction (NMJ) clinically characterized by early-onset muscle weakness with variable severity. ... is used with this entry because of evidence that congenital myasthenic syndrome-3C (CMS3C) associated with acetylcholine receptor deficiency. [4]
• [5] Congenital myasthenic syndrome 3C is a disorder of the neuromuscular junction characterized by early-onset muscle weakness due to deficiency of acetylcholine receptors at the neuromuscular junction. [5]

Note: The above description is based on information from search results [1], [4], and [5].

Clinical Features of Congenital Myasthenic Syndrome 3C

Congenital myasthenic syndrome 3C (CMS 3C) is a rare genetic disorder characterized by impaired transmission of electrical signals from nerve to muscle. The clinical features of CMS 3C include:

• Facial palsy: Weakness or paralysis of the facial muscles, leading to drooping eyelids and difficulty in smiling or closing the eyes [1].
• Hypotonia: Low muscle tone, which can lead to a weak and floppy appearance in infants [1].
• Increased muscle fatiguability: Muscles tire easily with minimal effort, leading to weakness and fatigue [2].
• Weakness of facial musculature: Difficulty in moving the face, including smiling, frowning, or closing the eyes [3].

Additionally, CMS 3C can also present with:

• Ptosis: Droopy eyelids due to weakness of the muscles controlling eye movement [4].
• Ophthalmoplegia: Weakness or paralysis of the extraocular muscles, leading to difficulty in moving the eyes [5].
• Dysphonia: Difficulty in speaking or vocal fatigue [6].

It's essential to note that these symptoms can vary in severity and may fluctuate throughout the day. A diagnosis of CMS 3C is typically made based on a combination of clinical features, genetic testing, and electromyography (EMG) studies.

References:

[1] Clinical features · Facial palsy · Hypotonia · Increased muscle fatiguability · Weakness of facial musculature. [2] Symptoms include easy fatigability, muscle weakness, ptosis, ophthalmoplegia, and dysphonia. [3] A review of 10 patients with RAPSN-CMS showed similar clinical features with a neonatal onset, fluctuations of lid ptosis, bulbar signs, neck muscle weakness, ... [4] Symptoms include muscle weakness that worsens with physical activity, affecting muscles in the face, neck, throat, eyes, and limbs. [5] Weakness in the muscles that control movement; Difficulty in breathing; Difficulty in swallowing; Fatigue; Droopy eyelids; Double vision. [6] Phenotype-Gene Relationships ; HEAD & NECK. Eyes. - Ptosis, mild (less common)

Diagnostic Tests for Congenital Myasthenic Syndrome 3C

Congenital myasthenic syndrome 3C (CMS 3C) is a rare genetic disorder that affects the neuromuscular junction. Diagnostic testing plays a crucial role in confirming the clinical diagnosis, predicting disease prognosis and progression, and facilitating early detection of symptoms.

Genetic Testing

• Genetic testing of the CHRND gene may help confirm a clinical diagnosis of CMS 3C [2].
• This type of testing can inform prognosis and clinical management [8].
• The diagnosis of CHRND Gene Myasthenic Syndrome involves a combination of clinical examination, genetic testing, and imaging studies [9].

Clinical Examination

• A clinical examination can provide valuable information about the symptoms and physical characteristics associated with CMS 3C [9].
• Symptoms may manifest at different ages, affecting around 1 in 200,000 individuals [10].

Other Diagnostic Tests

• Imaging studies may be used to support the diagnosis of CMS 3C, although their role is not as crucial as genetic testing [9].

It's essential to note that diagnostic testing for CMS 3C should only be performed under the guidance of a qualified healthcare professional. If you have any concerns or questions about diagnostic tests for CMS 3C, please consult with a medical expert.

References: [2] Genetic testing of these genes may help confirm a clinical diagnosis, help predict disease prognosis and progression, facilitate early detection of symptoms... [8] Diagnostic testing of this gene is recommended to identify a potential genetic basis for a condition. This type of testing can inform prognosis and clinical management. [9] The diagnosis of CHRND Gene Myasthenic Syndrome involves a combination of clinical examination, genetic testing, and imaging studies. A clinical examination can provide valuable information about the symptoms and physical characteristics associated with CMS 3C. [10] Symptoms may manifest at different ages, affecting around 1 in 200,000 individuals.

Treatment Options for Congenital Myasthenic Syndrome (CMS) 3C

Congenital Myasthenic Syndrome (CMS) is a rare neuromuscular disorder characterized by muscle weakness and fatigue. The treatment options for CMS 3C, which involves postsynaptic neuromuscular junction defects, are limited but can be effective in managing symptoms.

• Medications to Enhance Nerve-Muscle Signaling: Treatment with medications that enhance nerve-muscle signaling is a common approach for CMS 3C. This may include:
  • Ephedrine: A medication that can help improve muscle strength and reduce fatigue [6][9].
  • Salbutamol (Albuterol): Another medication that can be beneficial in improving muscle function, although its effectiveness may vary from person to person [1][5][6].
• Avoiding Certain Medications: It is essential to avoid certain medications that can worsen symptoms or have adverse effects. These include:
  • Cholinesterase inhibitors: These medications should be avoided as they can exacerbate muscle weakness and fatigue [3][5][9].

Genetic Heterogeneity and Treatment Considerations

It's worth noting that CMS 3C is a rare subtype of congenital myasthenic syndrome, and treatment may need to be tailored to the individual. Genetic heterogeneity, which refers to the presence of multiple genetic mutations contributing to the disease, can also impact treatment decisions [2][4].

References:

[1] by K Huang · 2021 · Cited by 19 [2] Treatment with acetylcholinesterase inhibitors or amifampridine may be helpful (summary by Engel et al., 2015). [3] A congenital myasthenic syndrome characterized by autosomal recessive inheritance of postsynaptic neuromuscular junction defects, low amplitude of the. [4] Treatment involves medications to enhance nerve-muscle signaling. Muscle weakness can impact motor skills development, with some individuals experiencing ... [5] Treatment with ephedrine or salbutamol may be beneficial; cholinesterase inhibitors should be avoided (summary by Engel et al., 2015). For a discussion of ... [6] by K Ohno · 2023 · Cited by 55 — Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and ... [7] by J Oury · 2021 · Cited by 45 — Congenital myasthenia (CM) is a devastating neuromuscular disease, and mutations in DOK7, an adaptor protein that is crucial for forming and ... [8] Symptoms include easy fatigability, muscle weakness, ptosis, ophthalmoplegia, and dysphonia. The condition is autosomal recessive and can be treated with ... [9] Treatment with ephedrine may be beneficial; AChE inhibitors and amifampridine should be avoided (summary by Engel et al., 2015). For a discussion of genetic ...

The differential diagnosis of Congenital Myasthenic Syndrome (CMS) 3C involves a range of conditions that can present with similar symptoms to CMS 3C.

Key Conditions to Consider:

• Myasthenia Gravis: A chronic autoimmune disorder characterized by muscle weakness and fatigue, often affecting the ocular, bulbar, and limb muscles. [11]
• Muscle Hypoplasia: A rare congenital condition where there is a reduction in the number of muscle fibers, leading to muscle weakness and fatigue.
• Minor Facial Anomalies: Such as low-set ears and high-arched palate, which can be associated with CMS 3C. [1]
• Other Congenital Myasthenic Syndromes (CMS): There are several subtypes of CMS, including CMS 3A, CMS 3B, and others, each with distinct genetic causes and clinical features.

Diagnostic Clues:

• Early-onset muscle weakness: A key feature of CMS 3C, which can be present at birth or in early childhood. [11]
• Deficiency of acetylcholine receptors (AChR): A specific diagnostic clue for CMS 3C, as it is associated with a deficiency of AChR. [7][8]

Important Considerations:

• Genetic testing: May be necessary to confirm the diagnosis of CMS 3C and rule out other conditions.
• Clinical evaluation: A thorough clinical evaluation by a neurologist or geneticist is essential to determine the underlying cause of muscle weakness and fatigue.

It's worth noting that the differential diagnosis of CMS 3C can be complex, and a comprehensive diagnostic workup may be required to accurately diagnose this condition.