A gene defect causing a novel progressive epilepsy with mental retardation, EPMR, maps to chromosome 8p
- Univ. of Helsinki (Finland); and others
EPMR (progressive epilepsy with mental retardation) is a newly discovered autosomal recessively inherited disorder which occurs with high frequency in an isolated rural population in Finland. So far 25 patients have been identified, 21 of whom are alive. Twenty-three patients share a common ancestor from the 18th century. The main features of EPMR are: normal early development, tonic-clonic seizures with onset between ages 5 and 10, and mental retardation which begins approximately 2 years after the onset of epilepsy and soon leads to deepening mental retardation. Adult patients do not manage their daily life without help. The EEG is normal at the onset of epilepsy but later progressive slowing of the background activity occurs. The etiology and pathogenesis of EPMR remain known. As this is a novel disease entity without any definitive diagnostic marker we wished to begin its elucidation by first defining its gene locus. A random search for linkage in four multiplex families (only 20 individuals tested) resulted in the finding of linkage to marker D8S264 with a lod score of 4.45 at zero recombination. The EPMR gene resides in a 7 centimorgan interval between marker loci AFM185xb2 and D8S262 with a maximum multipoint lod score of 7.03 at 1.8 centimorgans proximal to D8S264. Physically this region is very distal on 8p. Of the sixteen EPMR chromosomes haplotyped 15 were identical or almost identical. One chromosome, however, had a distinctly different haplotype raising the possibility of there being two different mutations or one very old mutation. These findings are a starting point toward isolating and characterizing the gene and its protein product. Physical mapping has been initiated by isolating nine YACs from the region.
- OSTI ID:
- 133324
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0051
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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