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Charcot-Marie-Tooth Disease (CMT) is a group of inherited disorders that affect the peripheral nerves, which are the nerves outside the brain and spinal cord. It is named after the three physicians who first described it in 1886: Jean-Martin Charcot, Pierre Marie, and Howard Henry Tooth. CMT leads to muscle weakness and atrophy, as well as sensory loss, primarily in the feet and legs, and later in the hands and arms. The progression and severity of symptoms can vary widely among individuals and different forms of the disease.

Causes and Genetics

CMT is caused by mutations in genes that affect the structure and function of the peripheral nerves. More than 80 genes have been identified that can cause CMT when mutated. The disease is genetically diverse, but the most common form is CMT1A, which is caused by a duplication of the PMP22 gene on chromosome 17. CMT can be inherited in several ways, including autosomal dominant, autosomal recessive, and X-linked patterns, depending on the specific gene mutation.

Symptoms

The symptoms of CMT usually begin in adolescence or early adulthood, but onset can occur at any age. The initial symptoms often include weakness of the foot and lower leg muscles, which may lead to foot drop and a high-stepped gait to avoid dragging the toes. As the disease progresses, individuals may experience muscle wasting in their feet, lower legs, and eventually hands and arms. Sensory loss may also occur, leading to numbness and decreased ability to feel pain or temperature changes. Balance problems and falls are common due to muscle weakness and sensory loss.

Diagnosis

Diagnosis of CMT is based on clinical examination, family history, and the results of nerve conduction studies and electromyography, which measure the electrical activity of muscles and the speed of nerve signals. Genetic testing can identify the specific gene mutation, confirming the diagnosis and allowing for genetic counseling.

Treatment

There is no cure for CMT, but treatment can help manage symptoms and improve quality of life. Physical therapy and occupational therapy can help maintain muscle strength and improve mobility. Orthopedic devices, such as braces or orthotic shoes, can help with walking and prevent injury. In some cases, surgery may be necessary to correct severe foot deformities. Pain management is also an important aspect of treatment, as some individuals may experience chronic pain.

Prognosis

The prognosis for individuals with CMT varies depending on the type of CMT and the severity of symptoms. Most people with CMT have a normal lifespan but may experience a gradual increase in disability. Early diagnosis and treatment can help manage symptoms and prevent complications.

Epidemiology

CMT is one of the most common inherited neurological disorders, affecting approximately 1 in 2,500 people worldwide. It affects both men and women of all ethnic groups.

Research

Ongoing research is focused on understanding the genetic and molecular basis of CMT, developing new treatments, and finding a cure. Gene therapy and molecular therapy are areas of particular interest.