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Genetic aspects of juvenile myoclonic epilepsy. Preliminary results Volume 13, issue 2, Avril - Mai - Juin 2001

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Authors
Service d’explorations neurologiques et d’épileptologie, CHU Gui-de-Chauliac, 2, avenue Émile-Bertin-Sans, 34000 Montpellier, France.

Two predisposing factors for juvenile myoclonic epilepsy (JME) have been located on Chr. 6p and 15q, respectively. These results have been confirmed or contradicted by various studies, as a result of persisting doubts about the precise mode of inheritance of JME. Our working hypothesis is that JME is transmitted according to a complex mode of inheritance, and that population based (index cases) and family-based (transmission disequilibrium) studies are best suited. In 1999, a campaign was organized in Southern France to collect index cases and their parents. This work continues previous campaigns while integrating new strategies. We undertook a large clinical evaluation of the phenotype in a consecutive population of 170 JME cases collected in Marseille and Nice (104 women and 66 men, 61 and 39% respectively). A family history of epilepsy was found in 24% of patients in first-degree relatives and in 17% of patients in second-degree relatives. Twelve percent of the patients belonged to multiplex families. Affected first-degree relatives were mostly siblings. A direct transmission of JME or of another form of idiopathic generalized epilepsy was uncommon (29% of the cases), including maternal transmission in 73% of such cases, vs 27% of paternal inheritance.