DM1 - Myotonic Dystrophy type 1

Steinert disease, also known as Myotonic Dystrophy type 1 (DM1), is a muscle disease characterized by myotonia and by multiorgan damage that combines various degrees of muscle weakness, arrhythmia and/or cardiac conduction disorders, cataract, endocrine damage, sleep disorders and baldness.

Myotonic Dystrophy is the most frequent of the adult-onset muscular dystrophies; its prevalence is estimated at 5:100 000 inhabitants and the incidence at 13:100,000. Diagnosis is confirmed by the demonstration of an abnormality at the 19q13-3 locus, with the use of molecular genetic techniques. Its transmission is autosomal dominant, and anticipation may occur, that is, disease may be more severe and occur earlier in offspring.

Genetic counseling is maybe delicate for Myotonic Dystrophy because of the great variability of clinical expression, both within and between families. Prenatal diagnosis is proposed especially for maternal transmission because of the severity of the possible neonatal forms. Management ideally includes multidisciplinary annual follow-up.

Disease course is usually slowly progressive but rapid deterioration may sometimes be observed. Life expectancy is reduced by the increased mortality associated with the pulmonary and cardiac complications. Treatment is symptomatic. That is, problems associated with Myotonic Dystrophy are treated individually. For example, surgery is available for correction of cataracts. Medication may be prescribed to counter the effects of myotonia. Heart problems will be treated by a heart specialist depending on what symptoms are experienced. Children with developmental delays can be assisted by speech therapy and a modified school environment. Remaining as active as possible is recommended for everyone with Myotonic Dystrophy. Today no effective cure is available for DM1.