Myotonic dystrophy type 1: clinical genetics and multisystem involvement

Myotonic dystrophy type 1 (DM1) is a multisystem disorder affecting patients of all ages. The two main symptoms of DM1 consist of myotonia (inability to relax muscles) and muscle weakness, but DM1 can potentially affect almost every organ system in the human body. DM1 is caused by an inherited CTG-repeat expansion in the DMPK gene. At this time, curative or disease-modifying treatment options are not yet available. Consequently, management of DM1 affected individuals focuses on monitoring disease progression and early detection of possible complications. Moreover, it is of great importance to provide adequate information to patients and their caregivers. The current thesis aimed to improve DM1 patient management by adding to the current knowledge of the genetic inheritance of DM1 and multisystem involvement. Specifically, the thesis pays attention to the inheritance of small-sized DM1 repeat expansions, to the cardiac follow-up of DM1 patients, and describes energy expenditure and body composition of affected individuals.