Congenital Myasthenic Syndrome is an inherited muscular disorder resulting from a genetic flaw at the neuromuscular junction, occurring in 1 or 2 per million births. There will be a fundraiser to help with Kate's medical expenses on Saturday, April 8th at the Porter Walmart with Barbeque sandwich with Chips and Drink for $5.00, Hot Dogs for $1.50, as well as brownies, cookies and cakes.
Donations to help with Kate’s medical expenses can be made to the:
Kate Wimberly Medical Fund
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More About Congenital Myasthenic Syndrome
It can be so tricky to recognize that many doctors are stumped when they meet a patient with this unusual neuromuscular disorder. Very little, if anything at all, is mentioned on CMS in standard medical text. The occurrence of CMS is reported to be 1 or 2 per million. Some researchers suggest that CMS is not uncommon – but rather, commonly misdiagnosed.
The disease causes muscle weakness (myasthenia) and unusual fatigue that can progress with age. Typically in CMS, muscles of the eyes, face and/or limbs are prominently affected, but sometimes the respiratory muscles are also compromised. Extra strain on the body, such as infection or emotional stress, can cause a severe aggravation of general and respiratory weakness called myasthenic crisis…..this can cause respiratory failure. The symptoms are caused by defects in the connection between nerve and muscle, the neuromuscular junction (NMJ).
How Is Congenital Myasthenic Syndrome Inherited?
With the exception of slow-channel CMS, the inheritance pattern for CMS is autosomal recessive. This means that it takes two copies of the defective gene — one from each parent — to cause the disease.
Slow-channel CMS is inherited in an autosomal dominant manner. This means that one copy of a defective ACh receptor gene is enough to cause the disease, so an affected parent has a 50 percent chance of passing the disease on to a child.
Function at the Junction
To understand the defects underlying CMS, it's important to understand how the neuromuscular junction (NMJ) normally works.
The NMJ is a type of synapse, a site of cell-to-cell communication, where a nerve cell can stimulate a muscle cell to contract and produce movement. The nerve cell, or presynaptic side of the NMJ, stimulates the muscle cell by releasing a chemical signal called acetylcholine (ACh). The ACh travels across a synaptic space to reach the postsynaptic surface of the muscle cell, where it triggers contraction by opening pores (or "channels") called ACh receptors. To shut off the signaling process, an enzyme called acetylcholinesterase (AChE) breaks down ACh in the synaptic space.
Congenital myasthenic syndromes (CMS) can be caused by genetic defects in either the presynaptic (the nerve cells), synaptic (the space between the nerve & muscle cells) or postsynaptic(the muscle cells) parts of the NMJ.
Presynaptic CMS is caused by decreased production or release of ACh at the NMJ. Presynaptic CMS symptoms commonly include episodic apnea (CMS-EA), where breathing stops briefly. Other symptoms include weakness of the eye, mouth and throat muscles, sometimes resulting in double vision and difficulty chewing or swallowing.
Postsynaptic CMS is caused by changes in the ACh receptors. Postsynaptic CMS symptoms can range from mild to severe. Symptoms in infancy include severe muscle weakness, feeding and respiratory problems, and delays in motor milestones such as sitting, crawling and walking. Childhood or adult onset symptoms may include difficulty raising the eyelids (ptosis) and fatigue, but usually they don't interfere with daily living. In one form of postsynaptic CMS (slow-channel CMS), severe weakness that begins in infancy or childhood can progress and lead to loss of mobility and respiratory problems in adolescence or later in life.
Synaptic CMS, a deficiency of AChE leads to excessive muscle stimulation, which ultimately damages the muscle. Synaptic CMS symptoms commonly include feeding and respiratory problems early in childhood and weakness causing delayed motor milestones, reduced mobility and curvature of the spine (scoliosis).
Why Mayo Clinic?
Mayo Clinic is a leader in diagnosing and treating congenital myasthenic syndromes (CMS). Mayo Clinic doctors have been at the forefront in identifying the gene mutations responsible for the syndromes and in developing successful treatments.
Different forms of CMS vary widely in their symptoms, from mild to severely disabling. With accurate diagnosis and appropriate therapy, even potentially fatal forms can usually be treated successfully.
Children treated for CMS at Mayo Clinic benefit from collaborative care by doctors and pediatric specialists in neurology, neuromuscular disease, orthopedics, ophthalmology, anesthesiology and other areas, working together to develop an effective treatment plan for each patient.
Specific medical information given in this document regarding Congenital Myasthenic Syndrome was pulled from the following websites: