Introduction: The most frequent mutations in the spectrum of epilepsy with febrile seizures plus are those in the voltage-dependent sodium channels or in the gamma-aminobutyric acid receptors.
Aim: To describe the clinical, electroencephalographic and genomic characteristics of patients with epilepsy with febrile seizures plus and compare them with those found in the literature.
Patients and methods: We analysed 26 patients who had been diagnosed with this condition and had had a targeted genetic study with the aim of collecting variables related to epidemiological data, characteristics of the epilepsy, development, complementary tests, antiepileptic treatments and genetic study.
Results: Nine patients presented generalised epilepsy with febrile seizures plus; six had Dravet's syndrome; six had borderline Dravet's syndrome; two had Doose's syndrome; and three of them had cryptogenic partial epilepsy. Genetic disorders were observed in 62% of the cases. The mean age of onset of epilepsy was 13.5 months and the age was lower (with statistically significant differences) in patients with positive genetic testing. Epileptic status was suffered by 58% of cases either at onset or in the development of the epilepsy. A total of 85% of cases were taking valproic acid and 58% displayed cognitive impairment. Complementary tests were performed in all the patients.
Conclusions: Epilepsies with febrile seizures plus make up a genetically heterogeneous group. Missense mutations were the most common in our study. Although it is difficult to establish phenotype-genotype correlations, patients with deletions showed typical or borderline Dravet's syndrome, whereas mutations in the gamma-aminobutyric acid receptor had less severe epilepsy.