Charcot Marie Tooth disease belongs to the genetically related disorders that mainly affect the nervous system of the patient.
Charcot-Marie-Tooth disease was named after the three significant physicians who were foremost in recognizing this disease. Charcot-Marie-Tooth disease is also called peroneal muscular atrophy and hereditary sensory and motor neuropathy. This disorder is composed of a cluster of peripheral nerve dysfunctions. Peripheral nerves are located outside the spinal cord and the brain. They provide sensory structures to the muscles of the limbs. These types of disorders are recognized as peripheral neuropathies.
What are the Types of Charcot-Marie-Tooth Disease?
Currently, there are many different types of Charcot-Marie-Tooth disease. These types may be caused by irregularities among myelin sheaths. Although there are many identified types of this disease, there are only three primary types. CMT1A is considered to be an autosomal disorder. This is caused by the replication of genotypes in chromosome (17) which brings the necessary instructions. These instructions are used in the creation of peripheral myelin protein (22). This protein is a crucial element of the myelin sheath. Abnormalities can arise when these elements come with a greater number than their usual quantity.
Persons with this disease may experience atrophy and weakness of the lower leg muscles. These symptoms may come about during adolescence, and later they may have sensory loss and hand weakness. Intriguingly, a different type of distinct neuropathy can occur which is termed as HNPP, or hereditary neuropathy with predisposition to pressure palsy. This condition resulted from an eradication of one of the peripheral myelin protein (22) genes. There is an irregular decrease in the levels of these genes. This event can result in an intermittent demyelinating neuropathy.
CMT1B is also an autosomal disorder that is caused by transmutation of the genetic makeup of a person. These elements contain instructions for producing P0 or myelin protein zero. This substance is another crucial element of the myelin sheath. The majority of these transmutations are spot mutations, which means that the error only occurred on a letter of the genetic code of DNA. CMT1C is caused by a genetic defect. Manifestations for this type are similar to CMT1A symptoms.
CMT2 is caused by the irregularities present in the peripheral nerve cell’s axon. This type does not include the involvement of the myelin sheath. Under this type are several subtypes that represented by the inscriptions from A-L. Every single subtype is categorized according to the linked clinical characteristics and the method of inheritance. The Dejerine-Sottas disorder of the CMT3 is a severe type of demyelinating neuropathy. This condition commences at birth. Infants with this disorder have severe weakness, muscle atrophy, and sensory deficits.
CMT4 consists of numerous subtypes of recessive autosomal demyelinating sensory and motor neuropathies. Every single subtype has resulted from various genetic transmutations. This disease may affect specific cultural populations. The disorder associated to the X-chromosome dominant disorder is called CMTX. The disease is caused by a spot mutation in a specific gene on the X-chromosome. The components of the faulty gene are located inside the Schwann’s cells.
What is the Risk Factor in Having Charcot-Marie-Tooth Disease?
The morbidity due to this disease is essentially derived from foot deformities and distal muscle weakness. In some instances, the phrenic nerve association in this disease can cause respiratory difficulties. The phrenic nerve is responsible in controlling the diaphragm activities of the patient. People who have a prominent family record of this disease will give them higher chances of having the disease than others.
What are the Manifestations of Charcot-Marie-Tooth Disease?
This condition has common neuropathy symptoms. It affects both sensory and motor nerves. A common feature involves weakness of the lower leg and foot muscles. This disease can result in a high-stepped bearing and foot drop with recurrent falls or tripping, foot malformations like hammertoes and high arches. These conditions are characterized by bending the middle joint of the toes upward. The manifestations are due to a feeble group of small muscles. As the disease progresses, muscle atrophy and weakness may occur in the patient’s hands.
The commencement of symptoms is frequently in early adulthood or adolescence. Nevertheless, manifestations can also be postponed until middle adulthood. The severity of manifestations differs in various patients and even for other family members who have the same disease. The development of the disease is slow. The pain that patients experience during the course of the disease ranges from mild to severe. In some instances, these people may exhibit weakness of the respiratory muscles. The symptoms of CMT make this condition very fatal.
How to Diagnose Charcot Marie Tooth Disease?
Diagnosing Charcot Marie Tooth disease starts with a regular family history, patient history, and neurological assessments. The patient will be interrogated about the duration and the nature of their manifestations especially if other members of the family have the disorder. The neurologic assessments are done by a physician to seek for evidence of weakness in the legs, arms, hands, and feet muscles. These patients may also have a sensory loss and decreased muscle tone. Nerve conduction tests are also performed in conjunction with electromyography tests to evaluate the patient’s sensory and motor activities.