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Familial hemiplegic migraine |
Sang Thrombose Vaisseaux. Volume 11, Number 8, 579-86, Octobre 1999, Mini-revues
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 Résumé
Article gratuit
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Author(s) : Anne Ducros |
Summary : Familial hemiplegic migraine is an autosomal dominant form of migraine with aura. The attacks are usually characterized by the occurrence of a motor deficit during the aura. This deficit is always associated with other aura symptoms (sensory, visual or speech disturbancies) and generally precedes the migrainous headache. Severe episods with confusion or coma, prolonged hemiplegia and fever, are observed in 40% of the patients. Age of onset, symptoms and frequency of attacks, as well as evolution of the disease are highly variable among the patients, even within a given family. In 20% of families, permanent cerebellar signs such as ataxia or nystagmus are observed. Familial hemiplegic migraine is genetically heterogeneous. A first gene, CACNA1A, located on chromosome 19 and encoding a neuronal calcium channel , is implicated in 50% of unselected families and in all families in which hemiplegic migraine is associated with ataxia. The disease is caused by point mutations in the CACNA1A gene. At least 50% of cases with familial hemiplegic migraine and ataxia are due to the same recurrent T666M mutation. A second gene, located on chromosome 1 but yet unidentified, is implicated in 20% of the families. Finally, 30% of the families are unlinked to chromosomes 19 and 1, indicating the existence of at least a third gene. Due to its genetic heterogeneity and to the important size of the sole identified gene, CACNA1A, genetic diagnosis of this condition remains difficult. |
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