Familial partial epilepsy

Familial partial epilepsy (also known as familial focal epilepsy) encompasses a group of inherited epilepsy syndromes characterized by seizures that originate from a specific region of the brain. Several distinct subtypes are recognized, including familial temporal lobe epilepsy (FTLE), autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), and familial epilepsy with variable foci (FEVF). These conditions primarily affect the central nervous system, with seizure semiology depending on the brain region involved. Temporal lobe forms may present with déjà vu, auditory or visual hallucinations, and impaired awareness, while frontal lobe forms typically cause brief nocturnal motor seizures with hyperkinetic movements. The genetic basis of familial partial epilepsies is heterogeneous. Mutations in several genes have been identified, including CHRNA4, CHRNB2, and CHRNA2 (encoding nicotinic acetylcholine receptor subunits in ADNFLE), LGI1 and RELN (associated with lateral temporal lobe epilepsy), and DEPDC5, NPRL2, and NPRL3 (components of the GATOR1 complex, implicated in familial focal epilepsy with variable foci). Inheritance is most commonly autosomal dominant with variable expressivity and incomplete penetrance, meaning that not all individuals carrying a pathogenic variant will develop seizures, and affected family members may have seizures arising from different brain regions. The age of onset is variable, ranging from childhood to adulthood, though many patients present in adolescence or early adulthood. Seizures are often relatively mild and may respond well to standard antiseizure medications such as carbamazepine, oxcarbazepine, or lacosamide. In ADNFLE, seizures frequently occur during sleep and may be misdiagnosed as parasomnias. Prognosis is generally favorable, with many patients achieving good seizure control with medication, although some individuals, particularly those with GATOR1 complex mutations, may have drug-resistant epilepsy and may be candidates for epilepsy surgery. Genetic counseling is recommended for affected families.

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