[Steinert disease].

Steinert disease, also known as myotonic dystrophy type 1, 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. It is the most frequent of the adult-onset muscular dystrophies; its prevalence is estimated at 1/20,000 inhabitants. Diagnosis is confirmed by the demonstration of an abnormality at the 19q13-2 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 often delicate for this condition 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.