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Myoclonic epilepsy of unverricht and lundborg (EPM1A)

Genes

Summary

Epilepsy, progressive myoclonic 1A (Unverricht and Lundborg) is a recessively inherited epileptic disorder of young children and adults due to misfunction of cystatin B, a proteinase inhibitor encoded by a gene at chromosome 21q22. Physiological function of CSTB is still unknown but it seems to have a role in downregulation of catepsins. Catepsins are involved in nonselective degradation of intracellular proteins to peptides and amino acids, and in downregulation of antigen processing and apoptosis. First clinical symptoms occur after a normal infancy and early childhood at the age of 6 to 15 years presenting with epileptic seizures followed soon later by myoclonic jerks. Attacks are easily provoked by varied stimuli, particularly after waking in the morning. The course of the disease is progressive and, without proper treatment, slowly leads to decline of mental and motor functions. Spike-and-wave pattern is a typical finding in EEG recording. Treatment with valproate has good response and the outcome of patients is markedly improved. Clinical diagnosis can be supported by a gene test for the founder mutation, a 12 nucleotide expansion at the promoter region of the gene.

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Selected publications

  • Pennacchio LA, Lehesjoki AE, Stone NE, Willour VL, Virtaneva K, Miao J, D'Amato E, Ramirez L, Faham M, Koskiniemi M, Warrington JA, Norio R, de la Chapelle A, Cox DR, Myers RM. Mutations in the gene encoding cystatin B in progressive myoclonus epilepsy (EPM1). Science. 1996 Mar 22;271(5256):1731-4. (Pubmed)
  • Joensuu T, Lehesjoki AE, Kopra O. Molecular background of EPM1-Unverricht-Lundborg disease. Epilepsia. 2008 Apr;49(4):557-63. Epub 2007 Nov 19. Review. (Pubmed)
  • Lehesjoki AE, Gardiner M. Editors In: Noebels JL, Avoli M, Rogawski MA, Olsen RW, Delgado-Escueta AV, editors. Progressive myoclonus epilepsy: Unverricht-Lundborg disease and Neuronal ceroid lipofuscinoses. Jasper's Basic Mechanisms of the Epilepsies [Internet]. 4th edition. Bethesda (MD): National Center for Biotechnology Information (US); 2012. (Pubmed)