Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.Myotonic dystrophy is a chronic, slowly progressing, highly variable inherited multisystemic disease. It is characterized by wasting of the muscles (muscular dystrophy), cataracts, heart conduction defects, endocrine changes, and myotonia. Myotonic dystrophy can occur in patients of any age.Two types of adult onset myotonic dystrophy exist. Type 1 (DM1), also called Steinert''s disease, has a severe congenital form and a milder childhood-onset form. Also called proximal myotonic myopathy (PROMM), myotonic dystrophy type 2 (DM2) is due to a different mechanism than DM1 and generally manifests with milder signs and symptoms.