[Steinert's disease (dystrophia myotonica). General review].

By comments of 9 tables the main clinical and genetic features of myotonic dystrophy are recalled. Due to a most variable penetrance and expressivity, the recognition of the adult form of this autosomal dominant disease can be difficult. Congenital myotonic dystrophy is a serious disease which represents a major genetic risk for the heterozygous women, which are often very slightly affected or even not aware of their disorder. For them, prenatal diagnosis is fully justified and now possible with a small risk of error by determination of DNA polymorphism. Preclinical detection in young adults can also be improved by this new method.