OBJECTIVE: This study aimed to further examine the impact of epileptic seizures on neurocognitive outcomes in KBG syndrome, a rare genetic neurodevelopmental disorder characterized by pathogenic variants in the gene ANKRD11. METHODS: A single clinician interviewed a cohort of individuals with genetically confirmed cases of KBG syndrome. Medical records and other relevant data were collected for each participant. To evaluate participants' adaptive functioning, trained professionals conducted assessments using the Vineland-3 Adaptive Behavior Scales. The assessment compared individuals with epilepsy to those without seizures and covered the domains of communication, daily living skills, socialization, and maladaptive behaviors. Further comparisons were drawn based on insights from interviews and information extracted from participants' medical records. RESULTS: While the KBG cohort displayed lower overall adaptive behavior composite scores compared to the average population, several members displayed standard scores at or higher than average, as well as higher scores compared to those with the neurodevelopmental disorder Ogden syndrome. Within the KBG cohort, males consistently scored lower than females across all domains, but none of these categories reached statistical significance. While the group with epilepsy exhibited overall lower scores than the non-seizure group in every category, statistical significance was only reached in the written communication subdomain. We predict this lack of significance is limited by low sample size, reducing study power. CONCLUSIONS: Due to the rarity of KBG syndrome, our research provides valuable insights that can aid in epilepsy screening and inform assessment strategies for neurocognitive functioning in those with this condition. The cohort performed overall higher than expected with outliers existing in both directions. Although our results suggest that seizures might influence the trajectory of KBG syndrome, the approaching but overall absence of statistical significance between study groups underscores the necessity for a more extensive cohort to discern subtle variations in functioning. Conducting Vineland-3 assessments in the KBG syndrome population can enhance research insights regarding differences between those with and without epilepsy. Given the data collected, we recommend vigilant monitoring for seizures following a KBG diagnosis, with consideration for performing baseline EEG assessments.

The authors have declared no competing interest.

This research was supported by funds provided to Gholson J. Lyon from the New York State Office for People with Developmental Disabilities. Additional funding was provided by several families with KBG syndrome along with seed funding by the KBG Syndrome Foundation.

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Both oral and written patient consent were obtained for research and publication, with approval of protocol #7659 for the Jervis Clinic by the New York State Psychiatric Institute - Columbia University Department of Psychiatry Institutional Review Board.

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All data produced in the present study are available upon reasonable request to the authors. Exome sequencing was done by clinical companies, so these underlying sequence data are private and not available. The genetic testing reports contain identifiable information, so cannot be shared.