Synonyms
Curschmann-Batten-Steinert Syndrome
DM
Myotonia Atrophica
Steinert Disease
Dystrophia Myotonia

Disorder Subdivisions
Myotonic Dystrophy type 1 (DM1)
Myotonic Dystrophy type 2 (DM2)

General Discussion
Myotonic Dystrophy (DM) is an inherited disorder involving the muscles, vision, and endocrine glands. It may also cause mental deficiency and loss of hair. The more obvious features of the disorder are muscle rigidity and the inability to relax a muscle or set of muscles after contraction. Onset of this rare disorder usually occurs during early adulthood. However, it may occur at any age and is extremely variable in degree of severity.

There appear to be at least two forms of this disorder. The more commonly encountered is called Myotonic Dystrophy type 1 (DM1) and results from a fault on chromosome 19. The second and less frequently encountered form is called Myotonic Dystrophy type 2 (DM2). DM2 is the consequence of one or more defects on chromosome 3.

The disorder is brought about by one or more failures or defects in the channel system through which electrolytes (substances that form ions when melted or dissolved in a suitable medium, becoming conductors of electricity) move in and out of muscle cells. DM is one of several channelopathies that may occur.