The progressive myoclonus epilepsies

The progressive myoclonus epilepsies (PME) are neurodegenerative diseases with prominent myoclonus and epilepsy. They are mostly, though not exclusively, diseases of children, and are mostly, though not exclusively, fatal. This review includes only those PME where more than one family has been described. The largest group of PME is the neuronal ceroid lipofuscinoses (NCL). The genetics of the NCL is representative of the larger group. Most, but not all, are monogenic, autosomal recessive inherited diseases, and most diseases genes, but not all, encode lysosomal proteins. One of the major questions in PME is "why PME"? That is, why do these neurodegenerative diseases result in so much epileptogenesis? Perhaps, the answers to "why epilepsy?" underlying this entire volume on genetics of epilepsy, will be aided by this group of the severest of epilepsies, where most, probably almost all, genes are already known. As therapies go, while not much is available yet, most of the PME start from a point of initial normalcy, and have a period of minimal symptoms close to onset, and most are relatively simple metabolic diseases. Hence, among the intractable epilepsies, hope for treatments and cures is likely the strongest in this group of diseases.