Symptoms in the congenital form of myotonic dystrophy are evident at birth. Affected infants show muscle weakness, respiratory defects, and eventually, mental retardation

People who have myotonic dystrophy have progressive muscle wasting and weakness beginning in their 20's or 30's. The muscle wasting and weakness develop in their lower legs, hands, neck and face.

Myotonic dystrophy does not have attributed behavior problems per se. However, Childhood and adolescent forms of the disease can exhibit cognitive difficulties which can present in a number of different ways such as attention deficit type disorders which could be mislabeled as behavior problems. Your best source of information on Myotonic Dystrophy on the web is the Myotonic Dystrophy Foundation.

Myotonic dystrophy is diagnosed clinically in individuals that have a specific type of muscle weakness. This is confirmed with molecular genetics testing, where the DMPK is analyzed

facial weakness and a slack jaw, drooping eyelids (ptosis ), and muscle wasting in the forearms and calves. A person with this dystrophy has difficulty relaxing his grasp, especially if the object is cold