Myotonic Dystrophy type 1 (DM1)
A chronic, slowly progressing, highly variable, inherited multisystemic disease. It is characterized by wasting of the muscles, cataracts, heart conduction defects, endocrine changes and myotonia. Two types of myotonic dystrophy exist. Type 1 (also called Steinert disease) has a severe congenital form and a milder childhood-onset form.