Myotonic dystrophy type 1 - updates on mechanisms of multisystemic manifestations, genetically targeted therapeutics, and preparing for a postapproval world.

PURPOSE OF REVIEW: Myotonic dystrophy type (DM1) is the most prevalent muscular dystrophy and manifests throughout the lifespan with signs and symptoms in all major organ systems. There are significant updates on therapeutic development and trials focused on muscle disease in DM1, as well as updates on the mechanism and progression of disease in nonmuscle tissues, changes or updates on clinical management, and the societal burden associated with a varied and prevalent disorder. RECENT FINDINGS: Evidence of improvement with strength and myotonia with genetically targeted treatments in early phase trials. Preparation for natural history studies to evaluate the impact of therapeutics on the heart and central nervous system (CNS), and expansion to early onset forms of DM1. Improvements in our understanding of mechanisms of CNS, cardiac, gastrointestinal, and liver manifestations. Evolving approaches to cardiac monitoring and respiratory care. DM1 is genetically more common than recognized clinically, and how this may affect societal disease burden. SUMMARY: This review highlights genetically targeted therapeutics showing impact for muscle manifestations of DM1, ongoing efforts now shifting to expand to other target tissues and the younger population, and, in preparation for a clinically available medicine, our understanding of societal burden and population genetics of DM1.