Myasthenia, familial

Myasthenia, Familial

Myasthenia, familial, is a rare genetic disorder characterized by muscle weakness and fatigue. It is a form of congenital myasthenic syndrome (CMS), which is a group of inherited neuromuscular disorders caused by defects at the neuromuscular junction. This condition is distinct from myasthenia gravis, which is an autoimmune disorder.

Pathophysiology

Familial myasthenia is caused by genetic mutations that affect the proteins involved in neuromuscular transmission. These mutations can occur in various genes, such as those encoding for the acetylcholine receptor, rapsyn, or other proteins critical for synaptic function. The result is impaired transmission of nerve impulses to muscles, leading to muscle weakness.

Clinical Presentation

Patients with familial myasthenia typically present with symptoms in infancy or early childhood. Common symptoms include:

• Muscle weakness that worsens with activity and improves with rest.
• Ptosis (drooping of the eyelids).
• Difficulty swallowing or speaking.
• Respiratory difficulties in severe cases.

The severity of symptoms can vary widely among individuals, even within the same family.

Diagnosis

Diagnosis of familial myasthenia involves a combination of clinical evaluation, genetic testing, and electrophysiological studies. Key diagnostic steps include:

• Clinical Evaluation: Assessment of muscle strength and fatigue patterns.
• Genetic Testing: Identification of mutations in genes associated with CMS.
• Electrophysiological Studies: Repetitive nerve stimulation tests to assess neuromuscular transmission.

Treatment

Treatment for familial myasthenia focuses on improving neuromuscular transmission and managing symptoms. Options include:

• Cholinesterase Inhibitors: Medications such as pyridostigmine that enhance communication between nerves and muscles.
• 3,4-Diaminopyridine: A drug that increases the release of acetylcholine at the neuromuscular junction.
• Supportive Therapies: Physical therapy and occupational therapy to maintain muscle function and quality of life.

Prognosis

The prognosis for individuals with familial myasthenia varies depending on the specific genetic mutation and the severity of symptoms. With appropriate management, many patients can lead relatively normal lives, although some may experience significant disability.

Also see

• Congenital myasthenic syndrome
• Myasthenia gravis
• Neuromuscular junction
• Genetic disorders

edit 

WikiMD neurology

External links

• Comprehensive information from the National Institute of health.
  

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z