Epidemiology and familial clustering of pediatric epilepsy in the geographic isolate of Ischia.

Background: Geographic isolates are the ideal setting to study the genetic background and the epidemiology of epilepsy. There are only few published reports on the epidemiology of pediatric epilepsy in geographic isolates.

Methods: This study was performed in the Ischia island, district of Napoli (Southern Italy). The local population includes 61,086 individuals, 8381 of them aged from 0 to 14 years. We included children with two or more unprovoked seizures or one unprovoked seizure associated to a high risk of relapse, observed from 2004 to 2017. Neonatal, febrile and acute symptomatic seizures were excluded. Eligible patients were identified through the local pediatricians' medical records. All probands and their parents underwent a face-to-face interview. Clinical charts were reviewed and electroclinical diagnoses were confirmed by two authors (AC, VB).

Results: Thirty-six children and adolescents were included. Overall, the prevalence of epilepsy in the Ischia island was 4.3 per 1,000 (95% CI 3.0-5.9). Incidence was 51.7 per 100,000 person-years (95% CI 36.2-71.6). Sixteen (44.4%) patients had a genetic (idiopathic) origin and 20 (55.6%) a symptomatic (structural/metabolic) etiology. Nine probands (25%) had at least one family member with epilepsy (including third-degree relatives). Their pedigrees were suggestive of dominant inheritance in six and of recessive inheritance in three families.

Conclusions: The epidemiological features of pediatric epilepsy in this geographic isolate are similar to the general population. A family history was reported in one fourth of the patients with a wide clinical heterogeneity, likely reflecting genetic heterogeneity in this population.