An Overview of Charcot-Marie-Tooth Disorders

Charcot-Marie-Tooth, or CMT, is the most commonly inherited neurological disorder and is found world-wide in all races and ethnic groups. Discovered in 1886 by three physicians, Jean-Martin-Charcot, Pierre Marie, and Howard Henry Tooth, CMT affects an estimated 2.6 million people.

CMT patients slowly lose normal use of their feet/legs and hands/arms as nerves to the extremities degenerate and the muscles in the extremities become weakened because of the loss of stimulation by the affected nerves. Many patients also have some loss of sensory nerve function.

CMT is one of the 40 diseases covered by the MDA, but unlike muscular dystrophy, in which the defect is in the muscles, CMT is a disorder in which the defect is in the nerves that control the muscles.

CMT usually isn’t life-threatening and almost never affects brain function. It is not contagious, but it is hereditary and can be passed down from one generation to the next. CMT...

• ...is also known as peroneal muscular atrophy (PMA) and hereditary motor sensory neuropathy (HMSN).
• ...is slowly progressive, causing deterioration of peripheral nerves which control sensory information and muscle function of the foot/lower leg and hand/forearm.
• ...causes degeneration of peroneal muscles (located on the front of the leg below the knees).
• ...causes foot-drop walking gait, foot bone abnormalities, high arches and hammertoes, problems with balance, problems with hand function, occasional lower leg and forearm muscle cramping, loss of some normal reflexes, scoliosis (curvature of the spine) and sometimes, breathing difficulties.
• ...does not affect life expectancy, but can, in rare instances, cause severe disability.
• ...has no cure, although physical therapy, occupational therapy and moderate physical activity are beneficial.
• ...is sometimes surgically treated.
• ...is usually inherited in an autosomal dominant pattern, which means if one parent has CMT there is a 50/50 chance of each child inheriting the disorder.
• ...may become worse if certain neurotoxic drugs are taken.
• ...can vary greatly in severity, even within the same family.
• ...can now be diagnosed by a blood test (CMT types: 1A, 1B, 1C, 1D, 1E, 1F, 1X, 2A, 2E, 2I, 2J, 2K, 4A, 4E, 4F, HNPP, CHN, and DSN).

For more on Charcot-Marie-Tooth disorders, click here to view a presentation by Michael E. Shy, MD, Professor of Neurology, Wayne State University School of Medicine, and Chairman of the CMTA Medical Advisory Board. Brought to you courtesy of Athena Diagnostics, this "Virtual Grand Rounds™" presentation requires Adobe Flash Player. (Don't have it? Click here to download and install it now.)