Dystrophic myotonia is a sufficiently rare disease inherited mainly by the 
autosomal dominant type. Clinical picture is characterized by the myotonic, 
myopathic, and endocrine-autonomic syndrome. A clinical, genetic, and 
electromyographic study was carried out to elucidate the problem of this 
condition inheritance, its intra- and interfamilial clinical polymorphism, and 
effects of environmental factors on its course and outcomes.