MYOTONIC DYSTROPHIES: GENETICALLY-BASED DISEASES DUE TO TOXIC RNA

Myotonic dystrophies (DMs, the second most diffuse forms of muscular dystrophy, after Duchenne dystrophy) are genetically-based degenerative neuromuscular diseases exhibiting widely variable clinical features and characterized by myotonia (i.e., a prolonged contraction of skeletal muscles after short stimulation) and a delayed muscle relaxation after voluntary contraction. There are two form of DMs: the more severe DM1 (or Steinert’s disease), and the milder form DM2. The intranuclear accumulation of expanded RNAs is considered as the pathogenetic factor of DMs: the presence of these RNAs exerts a toxic action on cell function which essentially depends on the ectopic sequestration of nuclear protein factors involved in the processing of transcripts. The aim of this mini-symposium is to describe the genetic and cellular bases of DMs, showing how the results of basic research may provide important clues for both diagnosis and therapy.