Progressive myoclonus epilepsies are a group of rare genetic diseases. The onset generally occurs around puberty in otherwise healthy children. They all involve myoclonus and epilepsy but then differ depending on the different symptoms that are related. The outlook of these diseases is nearly always unfavourable and treatment only focuses on symptoms. Much planning will be needed to improve the quality of life for these children who will gradually become over time more and more severely disabled. Among these diseases, the most notable is Unverricht-Lundborg disease and Lafora disease, among others. However, the genetic mechanism of these diseases is simple and has been perfectly identified over time thanks to advancements in scientific discoveries. Hope lies in gene therapy, which in the near future will most likely be able to optimise treatment and even cure these children. This book addresses the situation by relying on clinicians’ descriptions, studies led by biologists on genetic variations and mutations and the work carried out daily by numerous scientists researching into treatment. By retracing the history of these diseases, from discovery and identification of mutated genes to the review of syndromes they encompass, this book marks the path we have travelled but also the distance we have yet to go.