[Genetic and clinical characteristics in epilepsy patients with ATP6V1A gene variants]

Objective: To explore the genetic and clinical characteristics of epilepsy related with ATP6V1A gene heterozygous variants. Methods: A case series study was conducted. The clinical data of 10 children of epilepsy associated with ATP6V1A gene variants who were admitted to the Children's Medical Center, Peking University First Hospital from January 2019 to December 2024 was collected. The characteristics of children' gene variation, clinical phenotype, auxiliary examination results, treatment and prognosis were analyzed. Results: Among the 10 children, there were 4 boys and 6 girls. All 10 children with ATP6V1A gene variants were de novo heterozygous variants, including 1 case of mosaic variant. A total of 9 different variants were identified and 7 variants have not been reported previously. The age at epilepsy onset was 28 (9, 48) months. Five children experienced their first seizure as a fever induction. The types of epileptic seizures included focal seizures in 6 children, epileptic spasms in 5 children, tonic spasms and atonic seizures in 1 child respectively. Three children had 2 seizure types. Global developmental delays were exhibited in 8 children, 2 of whom manifested autism spectrum disorder phenotypes. Two children showed normal development. Electroencephalography revealed slowed background activity in 5 children. Interictal epileptiform discharges were recorded in 9 cases, including hypsarrhythmia, focal, multifocal or generalized discharges. Clinical seizures were captured in 4 children. Brain magnetic resonance imaging abnormalities were found in 4 children, including frontotemporal cortical dysplasia, prominent sulci, delayed myelination of white matter, dysplasia of the corpus callosum, bilateral ventricular enlargement, and cerebral atrophy. Five children were diagnosed with developmental and epileptic encephalopathy (DEE), and 4 of them were diagnosed with infantile epileptic spasms syndrome. At the last follow-up, the age was 78 (25, 120) months. Seizures were controlled in 6 children, while 4 children had uncontrolled seizures despite treatment with ≥3 anti-seizure medications. Conclusions: All children with ATP6V1A gene related epilepsy harbored de novo heterozygous missense variants, with few showing mosaic variants. Seizure onset age ranged widely from the neonatal period to childhood. The predominant seizure types were focal seizures and epileptic spasms. The phenotypic spectrum may exhibit DEE, while a minority maintain normal development.