Juvenile myoclonic epilepsy

Juvenile myoclonus epilepsy (JME) is a common epileptic syndrome, the etiology of which is genetically determined. Its onset occurs from 6 through 22 years of age, and affected patients present with myoclonic jerks, often associated with generalized tonic-clonic seizures - the most common association - and absence seizures. JME is non-progressive, and there are no abnormalities on clinical examination or intellectual deficits. Psychiatric disorders may coexist. Generalized polyspike-and-waves are the most characteristic electroencephalographic pattern. Usual neuroimaging studies show no abnormalities. Atypical presentations should be entertained, as they are likely to induce misdiagnosis. Prevention of precipitating factors and therapy with valproic acid (VPA) are able to control seizures in the great majority of patients. Whenever VPA is judged to be inappropriate, other antiepileptic drugs such as lamotrigine may be considered. Treatment should not be withdrawn, otherwise recurrences are frequent.

A epilepsia mioclônica juvenil é uma síndrome epiléptica comum, cuja etiologia é fundamentada na genética. Inicia-se entre 6 e 22 anos e os indivíduos apresentam mioclonias, que podem ser acompanhadas por crises tônico-clônicas generalizadas - associação mais comum - e crises de ausência. A doença não é progressiva, e não há alterações detectáveis no exame físico ou déficits intelectuais. Distúrbios psiquiátricos podem coexistir. Polipontas-ondas lentas generalizadas constituem o padrão eletrencefalográfico ictal típico. Não há anormalidades em exames de imagem convencionais. Apresentações atípicas devem ser consideradas, pois predispõem a erros de diagnóstico. A prevenção de fatores desencadeantes e o uso de ácido valpróico (VPA) controlam as crises epilépticas na grande maioria dos casos. Quando o VPA é inapropriado, outras drogas como a lamotrigina podem ser utilizadas. O tratamento não deve ser interrompido, visto que as recidivas são freqüentes.

Absence of GABRA1 Ala322Asp mutation in juvenile myoclonic epilepsy families from India.

An Ala322Asp mutation in the GABRA1 gene was recently reported to be responsible for causing the autosomal dominant (AD) form of juvenile myoclonic epilepsy (JME) in a French-Canadian family. To study if JME families from India exhibiting the AD mode of inheritance carry the Ala322Asp mutation, we examined 35 unrelated JME-affected individuals from such families for the Ala322Asp mutation in GABRA1. Ala322Asp mutation was not observed in any of these JME-affected individuals, suggesting that this mutation is unlikely to be a predominant mutation involved in causation of epilepsy. To evaluate the possibility of other mutation(s) in and around GABRA1 that may predispose to JME, we compared the allele frequencies at two marker loci, D5S2118 and D5S422, flanking GABRA1, in probands and 100 matched population controls. One of the allele frequencies at D5S422 shows a significant difference between the cases and controls (chi-square = 11.44, d.f. = 1, P = 0.0007), suggesting genetic association between JME and genes located in the proximity of the DNA marker.