Charcot-Marie-Tooth Disorder (CMT)

Charcot-Marie-Tooth disorder (CMT) is an inherited neurological disease
characterized by a slowly progressive degeneration of the muscles in the
foot, lower leg, hand, and forearm, and a mild loss of sensation in the
limbs, fingers, and toes. The first sign of CMT is generally a high arched
foot or gait disturbances. Other symptoms of the disorder may include foot
bone abnormalities such as high arches and hammer toes, problems with hand
function and balance, occasional lower leg and forearm muscle cramping, loss
of some normal reflexes, occasional partial sight and/or hearing loss, and,
in some patients, scoliosis (curvature of the spine).
CMT is a disorder of genetic heterogeneity, in which mutations in different
genes can produce the same clinical symptoms. In CMT, there are not only
different genes but different patterns of inheritance. The most common type,
CMT1A, is inherited in an autosomal dominant pattern. This means that if one
parent has CMT there is a 50 percent chance of passing the disease on to
each child. Other types are autosomal recessive or sex-linked CMT. Each type
is characterized by symptoms ranging from severe weakness and wasting of leg
and hand muscles to very mild symptoms or no symptoms at all. Full
expression of CMT's clinical symptoms generally occurs by age 30. The more
severe symptoms are related to an earlier age of onset.