Program in Genetics and Genome Biology and Division of Neurology, Department of Paediatrics, The Hospital for Sick Children and the University of Toronto, Canada
Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, ‘G. Gaslini’ Institute, Genova, Italy
Centre Saint-Paul, Hôpital Henri-Gastaut, France
Department of Anatomic Pathology, Hospital Sao Joao, Porto, Portugal
Division of Pathology, Department of Pathology and Laboratory Medicine, The Hospital for Sick Children and the University of Toronto, Canada
Correspondence: Berge A. Minassian
Program in Genetics and Genome Biology and Division of Neurology,
Department of Paediatrics,
The Hospital for Sick Children and the University of Toronto,
- Key words: Lafora, laforin, malin, glycogen phosphatase, ubiquitin, EPM2A, EPM2B, progressive myoclonus epilepsies
- DOI : 10.1684/epd.2016.0842
- Page(s) : 38-62
- Published in: 2016
Lafora disease (LD) is an autosomal recessive progressive myoclonus epilepsy due to mutations in the EPM2A (laforin) and EPM2B (malin) genes, with no substantial genotype-phenotype differences between the two. Founder effects and recurrent mutations are common, and mostly isolated to specific ethnic groups and/or geographical locations.
Pathologically, LD is characterized by distinctive polyglucosans, which are formations of abnormal glycogen. Polyglucosans, or Lafora bodies (LB) are typically found in the brain, periportal hepatocytes of the liver, skeletal and cardiac myocytes, and in the eccrine duct and apocrine myoepithelial cells of sweat glands. Mouse models of the disease and other naturally occurring animal models have similar pathology and phenotype. Hypotheses of LB formation remain controversial, with compelling evidence and caveats for each hypothesis. However, it is clear that the laforin and malin functions regulating glycogen structure are key.
With the exception of a few missense mutations LD is clinically homogeneous, with onset in adolescence. Symptoms begin with seizures, and neurological decline follows soon after. The disease course is progressive and fatal, with death occurring within 10 years of onset. Antiepileptic drugs are mostly non-effective, with none having a major influence on the progression of cognitive and behavioral symptoms. Diagnosis and genetic counseling are important aspects of LD, and social support is essential in disease management.
Future therapeutics for LD will revolve around the pathogenesics of the disease. Currently, efforts at identifying compounds or approaches to reduce brain glycogen synthesis appear to be highly promising.