Congenital Myasthenic Syndromes (CMS)

What is Congenital Myasthenic Syndromes?

Congenital myasthenic syndromes, or CMS, are a class of specific disorders that affect the transference of nerve cells to various muscles in the body. The inception, severity and impacted muscle groups are different for each person who is diagnosed with the disorder. Common types of congenital myasthenic syndromes include presynaptic CMS, fast-channel and slow-channel postsynaptic CMS, and synaptic CMS.

These conditions occur due to a gene mutation that disrupts the operation of the neuromuscular junction. The nerve cell, the muscle cell or the opening that is between them can be affected. Individuals who acquire this disorder have inherited it from one or both parents, depending on the specific type.

What are the Symptoms of Congenital Myasthenic Syndromes?

People who have congenital myasthenic syndromes experience weakness in their muscles, especially during physical activities. The cranial nerves are often affected and this causes weak facial muscles, eyelids that droop and double vision. A person’s speech may be affected and this causes them to slur their words while speaking. Difficulty swallowing may also occur due to weakened muscles in the throat. Infants who have CMS may not be able to hold up their head by themselves and they are often slow at developing their motor skills, such as crawling and walking. Respiratory issues are also a symptom of CMS and infants who are extremely weak may have difficulties eating.

Congenital Myasthenic Syndromes Causes

The common cause of congenital myasthenic syndromes is genetics, disturbing the junction where the nerve triggers muscle movement. The inherited autosomal recessive gene exists in both parents, who pass the altered gene on to their child. Symptoms appear after birth or early childhood. Severity varies from slight to high concentrations of muscle weakness.

There are over twenty different genes identified to cause congenital myasthenic syndromes as unique as each individual. Sometimes the condition occurs with no family history or illness associated with the disease.

Families with a history of this condition increase the risk by passing the inherited trait to their offspring. Although parents may not exhibit symptoms of the disorder, each parent passes on one abnormal gene and one normal gene, forming a 25% risk of affecting the next generation. Children born from two carrier parents raise the risk by 50% when passing the defective gene on to their grandchild.

How is a Congenital Myasthenic Syndromes Treated?

The symptoms of presynaptic CMS and fast-channel postsynaptic CMS are often treated with cholinesterase inhibitors, such as pyridostigmine and amifampridine. These types of drugs are prescribed to help an individual’s muscles function normally. Physicians prescribe quinidine or fluoxetine to people who have been diagnosed with slow-channel postsynaptic CMS. Additional drugs that are prescribed to individuals with congenital myasthenic syndromes include salbutamol and ephedrine, which are adrenergic agonists.

There are no types of medications available to treat synaptic CMS.

Congenital Myasthenic Syndromes Prevention

This condition is rare with no cure or method of prevention for passing the genetic mutation on to the offspring. If you have a family history of this disorder, genetic testing is mandatory. Your doctor can help with scheduling the tests. The analysis will classify the gene responsible for the condition serving to determine the exact treatment.

You need to talk with your doctor, since individuals react differently to treatments or medications used for the condition. Get as much information on the condition as possible and increase your understanding about the medications with adverse effects on the disorder to prevent harmful reactions.

Some treatments influence the neuromuscular signals, improving motor skills and lessening fatigue. Other treatments manage the respiratory difficulties following excitement, fever or infections. Early genetic information can prevent respiratory failure of newborn or young children.