Genetic factors play a major role in the aetiology of idiopathic generalised epilepsies (IGEs). The present genome scan was designed to identify susceptibility loci that predispose to a spectrum of common IGE syndromes. Our collaborative study included 130 IGE-multiplex families ascertained through a proband with either an idiopathic absence epilepsy or juvenile myoclonic epilepsy, and one or more siblings affected by an IGE trait. In total, 413 microsatellite polymorphisms were genotyped in 617 family members. Non-parametric multipoint linkage analysis, using the GeneHunter program, provided significant evidence for a novel IGE susceptibility locus on chromosome 3q26 (Z(NPL) = 4.19 at D3S3725; P = 0.000017) and suggestive evidence for two IGE loci on chromosome 14q23 (Z(NPL) = 3.28 at D14S63; P = 0.000566), and chromosome 2q36 (Z(NPL) = 2.98 at D2S1371; P = 0.000535). The present linkage findings provide suggestive evidence that at least three genetic factors confer susceptibility to generalised seizures in a broad spectrum of IGE syndromes. The chromosomal segments identified harbour several genes involved in the regulation of neuronal ion influx which are plausible candidates for mutation screening.

Sixty-one pediatric patients (12-229 months of age) with refractory epilepsy were treated with vigabatrin [gamma-vinyl GABA (GVG)] in a 16-week, single-blind, add-on, placebo-controlled trial. Twenty-three patients (38%) showed a reduction of more than 50% in seizure frequency; 12 patients (20%) experienced a seizure increase; and the remaining 26 did not show significant differences between placebo and GVG treatment. Among the 216 patients who entered the long-term phase after having experienced more than 50% decrease in seizure frequency, 14 continued with the same degree of improvement after 2-11 months of follow-up (mean 7.7). GVG was particularly efficient in cryptogenic partial epilepsy. Conversely, nonprogressive myoclonic epilepsy tended to be aggravated. Agitation was the most commonly observed side effect, mainly at onset of therapy in mentally retarded patients, but was easily reversed by dose reduction. GVG is a promising drug in the treatment of refractory epilepsies of childhood.

Sixty-six children with various types of severe drug-resistant epilepsy were entered into a long-term, dose-rising study of vigabatrin after a 4-week run-in placebo period. All the children were receiving one to three other antiepileptic drugs, the doses of which were not changed during the 6-month dose titration phase. Following the introduction of vigabatrin, 11 patients became seizure free, and 28 responded with a greater than 50% reduction in seizure frequency. The following types of epilepsy responded favorably in order of decreasing efficacy: cryptogenic and symptomatic partial epilepsy, other symptomatic generalized epilepsy, and Lennox-Gastaut syndrome. However, three of nine patients with myoclonic epilepsy showed an increase in seizure frequency. Optimal responses were found with vigabatrin doses of 40 to 80 mg/kg/ day, although no significant adverse effects were noted with doses of higher than 100 mg/kg/day. Thirty-eight responders continued on vigabatrin, 19 of whom have been treated for more than 1 year, with generally good efficacy. As a result of discontinuing concomitant antiepileptics, six patients are on monotherapy with vigabatrin, four of whom are seizure free. Vigabatrin tolerability was good, with 39 of 66 children reporting no adverse effects. Hyperkinesia was reported in 17 patients (26%), and two had to drop out of the study. All these patients had a history of hyperkinesia or mental retardation. In patients in whom vigabatrin dose was reduced because of hyperkinesia, a dose increase could later be instituted without recurrence of symptoms. There was no change in neurologic examination and no drug-related abnormalities in clinical laboratory data. It is concluded that this study shows that vigabatrin is safe and effective in the treatment of refractory epilepsy of various types in children. The recommended starting dose is 40 mg/kg/day, which can be increased up to 80 mg/kg/day, depending on clinical response. (J Child Neurol 1991;6(Suppl):2S30-2S37).