One of the objectives of this report is to provide a summary of the state of knowledge regarding the genotypic analysis of individuals with myotonic dystrophy and screening for carriers of the causative mutation, and to assess the usefulness of offering such a service in Quebec's health-care system. The report therefore deals with the clinical and genetic aspects of the disease, the test validity, and the screening-and-diagnosis strategy. It also describes the situation in Quebec with regard to these different aspects, the organization of laboratory services, and genetic test needs. Lastly, it provides an overview of the social and ethical issues raised by such a technological development.