Localization of a gene for benign adult familial myoclonic epilepsy to chromosome 8q23.3-q24.1

Familial adult onset myoclonic epilepsy associated with migraine

We report a new type of migraine associated epileptic syndrome in a family: adult onset myoclonic epilepsy with benign course and migraine. Affected members of the family had myoclonic and rare generalised tonic-clonic seizures. Most of the patients, but not all, had a history of migraine. Also, some cases of the family had only migraine. This family will be discussed because of two distinct features. Firstly, in this family a different type of epilepsy, adult onset myoclonic epilepsy was diagnosed that has not been classified in the ILAE 1989, classification(s), but was similar to that previously reported in Japanese families. Secondly, in most of the cases migraine was associated with the epilepsy.

Mapping of a locus for a familial autosomal recessive idiopathic myoclonic epilepsy of infancy to chromosome 16p13

Myoclonic epilepsies with onset in infancy and childhood are clinically and etiologically heterogeneous. Although genetic factors are thought to play an important role, to date very little is known about the etiology of these disorders. We ascertained a large Italian pedigree segregating a recessive idiopathic myoclonic epilepsy that starts in early infancy as myoclonic seizures, febrile convulsions, and tonic-clonic seizures. We typed 304 microsatellite markers spanning the 22 autosomes and mapped the locus on chromosome 16p13 by linkage analysis. A maximum LOD score of 4.48 was obtained for marker D16S3027 at recombination fraction 0. Haplotype analysis placed the critical region within a 3.4-cM interval between D16S3024 and D16S423. The present report constitutes the first example of an idiopathic epilepsy that is inherited as an autosomal recessive trait.

Genetics of the epilepsies

Molecular genetic analysis of mendelian epilepsies in humans and mice has revealed a diversity of underlying genes in symptomatic epilepsies associated with disordered brain development and neuronal survival. In contrast, the idiopathic mendelian epilepsies have emerged as a new category of channelopathies. New epilepsy loci have been mapped and one new epilepsy gene isolated. Functional analysis of epilepsy genes is providing new insights into the pathways that lead from mutant gene to hyperexcitable neurones. The major challenge for the future is the analysis of genetic epilepsies with complex inheritance.