What is the progression of CMT?ĭepending on the type of CMT, onset can be from birth to adulthood, and progression is typically slow. 4,5 For more on causes and inheritance patterns in CMT, see Causes/Inheritance. 3ĬMT can be inherited in several ways: autosomal dominant (through a faulty gene contributed by either parent) autosomal recessive (through a faulty gene contributed by each parent) or X-linked (through a gene on the X chromosome contributed by either parent). 2 The vast majority of cases are attributed to mutations in just four of these genes: PMP22, MPZ, GJB1, and MFN2. More than 30 genes have been implicated in CMT, each one linked to a specific type (and in many cases, more than one type) of the disease. What causes CMT?ĬMT is caused by defects in the genes that are responsible for creating and maintaining the myelin (insulating sheath around many nerves, increasing conductivity) and axonal structures. If the nerves that go to and from the diaphragm or intercostal (between the ribs) muscles are affected, respiratory impairment can result. CMT also often causes contractures (stiffened joints due to abnormal tightening of muscles and associated tissues), and sometimes, curvature of the spine (scoliosis or kyphosis).Īt the severe end of the CMT spectrum, the disease can affect nerves other than those that go to and from the extremities. Sometimes the hands, wrists, and forearms are affected as well. What are the symptoms of CMT?ĬMT causes muscle weakness and reduction in size (atrophy), and some loss of sensation in the lower legs and feet. CMT causes damage to the peripheral nerves, which carry signals from the brain and spinal cord to the muscles and relay sensations, such as pain and touch, to the brain and spinal cord from the rest of the body. The overall estimated prevalence of CMT is approximately 19 instances per 100,000 people, which varies between. The term “CMT” is regarded as being synonymous with hereditary motor sensory neuropathy (HMSN). Charcot-Marie-Tooth Disease (CMT) What is Charcot-Marie-Tooth disease (CMT)?Ĭharcot-Marie-Tooth disease (CMT) is a spectrum of nerve disorders named after the three physicians who first described it in 1886 - Jean-Martin Charcot and Pierre Marie of France and Howard Henry Tooth of the United Kingdom.