Genetic mapping of a new Lafora progressive myoclonus epilepsy locus (EPM2B) on 6p22.
BACKGROUND
Lafora disease is a progressive myoclonus epilepsy with polyglucosan accumulations and a peculiar neurodegeneration with generalised organellar disintegration. It causes severe seizures, leading to dementia and eventually death in early adulthood.


METHODS
One Lafora disease gene, EPM2A, has been identified on chromosome 6q24. Locus heterogeneity led us to search for a second gene using a genome wide linkage scan in French-Canadian families.


RESULTS
We mapped a second Lafora disease locus, EPM2B, to a 2.2 Mb region at 6p22, a region known to code for several proteins, including kinesins. Kinesins are microtubule dependent motor proteins that are involved in transporting cellular components. In neurones, they play a major role in axonal and dendritic transport.


CONCLUSIONS
Analysis of the present locus in other non-EPM2A families will reveal whether there is further locus heterogeneity. Identification of the disease gene will be of major importance towards our understanding of the pathogenesis of Lafora disease.
Chan
E M
EM
Program in Genetics and Genomic Biology, The Hospital for Sick Children and Department of Molecular and Medical Genetics, The University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8, Canada.
Bulman
D E
DE
Paterson
A D
AD
Turnbull
J
J
Andermann
E
E
Andermann
F
F
Rouleau
G A
GA
Delgado-Escueta
A V
AV
Scherer
S W
SW
Minassian
B A
BA
D002874:Chromosome Mapping / Q000379:methods; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics*; D005192:Family Health; D005260:Female; D006239:Haplotypes; D006801:Humans; D020192:Lafora Disease / Q000235:genetics* / Q000473:pathology; D008126:Lod Score; D008297:Male; D018895:Microsatellite Repeats; D010375:Pedigree