SUMMARYMutations in the KCNQ2 gene encoding for voltage-gated potassium channel subunits have been found in patients affected with early onset epilepsies with wide phenotypic heterogeneity, ranging from benign familial neonatal seizures (BFNS) to epileptic encephalopathy with cognitive impairment, drug resistance, and characteristic electroencephalography (EEG) and neuroradiologic features. By contrast, only few KCNQ3 mutations have been rarely described, mostly in patients with typical BFNS. We report clinical, genetic, and functional data from a family in which early onset epilepsy and neurocognitive deficits segregated with a novel mutation in KCNQ3 (c.989G>T; p.R330L). Electrophysiological studies in mammalian cells revealed that incorporation of KCNQ3 R330L mutant subunits impaired channel function, suggesting a pathogenetic role for such mutation. The degree of functional impairment of channels incorporating KCNQ3 R330L subunits was larger than that of channels carrying another KCNQ3 mutation affecting the same codon but leading to a different amino acid substitution (p.R330C), previously identified in two families with typical BFNS. These data suggest that mutations in KCNQ3, similarly to KCNQ2, can be found in patients with more severe phenotypes including intellectual disability, and that the degree of the functional impairment caused by mutations at position 330 in KCNQ3 may contribute to clinical disease severity.

Rufinamide may be an effective and well-tolerated adjunctive drug for the treatment of refractory childhood-onset epileptic encephalopathies other than Lennox-Gastaut syndrome. Rufinamide was most effective in patients with drop-attacks and (bi)frontal spike-wave discharges.

This is the first multicenter Italian experience with rufinamide as an adjunctive drug in children, adolescents and adults with Lennox-Gastaut syndrome. The patients were enrolled in a prospective, add-on, open-label treatment study from 11 Italian centers for children and adolescent epilepsy care. Forty-three patients (26 males, 17 females), aged between 4 and 34 years (mean 15.9 ± 7.3, median 15.0), were treated with rufinamide for a mean period of 12.3 months (range 3-21 months). Twenty patients were diagnosed as cryptogenic and 23 as symptomatic. Rufinamide was added to the baseline therapy at the starting dose of 10mg/kg body weight, evenly divided in two daily doses and then increased by 10mg/kg approximately every 3 days up to a maximum of 1000 mg/day in children aged ≥4 years with a body weight less than 30 kg. In patients more than 30 kg body weight, rufinamide could be titrated up to 3200 mg/day. After a mean follow-up period of 12.3 months (range 3-21 months), the final mean dose of rufinamide was 33.5mg/kg/24h (range 11.5-60) if combined to valproic acid, and of 54.5mg/kg/24h (range 21.8-85.6) without valproic acid. The response rate (≥50% decrease in countable seizures) was 60.5% (26 of 45 patients) in total; 51.1% experienced a 50-99% reduction in seizure frequency and complete seizure control was achieved in the last 4 weeks follow-up by 9.3% of patients. Two patients (4.7%) had a 25-50% seizure reduction, while seizure frequency remained unchanged in 13 (30.2%) and increased in 2 (4.7%). Reliable data for atypical absence seizures and myoclonic seizures were not available, as these are usually impossible to count. Ten patients (23.2%) reported adverse side effects, while taking rufinamide. They were generally mild and transient and most frequently included vomiting, drowsiness, irritability and loss of appetite. In conclusion, rufinamide as an adjunctive therapy reduced the number of drop attacks and major motor seizures in about 60% of patients with Lennox-Gastaut syndrome and produced only mild or moderate adverse side effects.

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See Karakaya and Wirth (doi:10.1093/brain/awz273) for a scientific commentary on this article. Neurofascin (NFASC) isoforms are immunoglobulin cell adhesion molecules involved in node of Ranvier assembly. Efthymiou et al. identify biallelic NFASC variants in ten unrelated patients with a neurodevelopmental disorder characterized by variable degrees of central and peripheral involvement. Abnormal expression of Nfasc155 is accompanied by severe loss of myelinated fibres.