# Epilepsy as a Component of the Dysmorphic–Neurodevelopmental Phenotype in Pediatric Patients with Recurrent Copy Number Variants

## TL;DR

The study finds that epilepsy is a common feature in children with certain genetic copy number variants, supporting the use of genetic testing in diagnosing these cases.

## Contribution

The study identifies specific CNV hotspots strongly associated with epilepsy and other neurodevelopmental features in pediatric patients.

## Key findings

- Epilepsy was diagnosed in 28.2% of 177 children with specific CNVs.
- The del16p11.2 deletion was the most frequent CNV, with 25.6% of those patients having epilepsy.
- The highest proportion of epilepsy was observed in patients with del1p36 and del1q21.1 CNVs.

## Abstract

Objective: Copy number variants (CNVs) overlapping genes associated with neurodevelopmental disorders in patients with epilepsy are particularly concentrated in epilepsy hotspot loci. The aim of this study was to evaluate epilepsy as a component of the dysmorphic–neurodevelopmental phenotype in patients with recurrent CNVs. Methods: The study included genetic and clinical data from 177 pediatric patients carrying 17 recurrent CNVs showing well-documented enrichment in epilepsy or associated with genetic OMIM syndromes. Results: Epilepsy was diagnosed in 50 of 177 children (28.2%), developmental delay in 147 (83.0%), dysmorphic features in 104 (58.8%), behavioral problems in 62 (35.0%), and congenital anomalies in 55 (31.1%). Among recurrent CNV hotspots, the del16p11.2 BP4–BP5 deletion was the most frequent, occurring in 39 of 177 patients. Ten children (25.6%) with del16p11.2 presented with epilepsy as part of the phenotype. Other frequently represented CNVs included del15q11.2 BP1–BP2 (OMIM #615656; 19/177 patients, 4/19 with epilepsy), del1q21.1 (OMIM #612474; 15/177, 6/15 with epilepsy), del15q13.3 (OMIM #612001; 13/177, 4/13 with epilepsy), and dup16p11.2 (OMIM #614671; 12/177, 1/12 with epilepsy). The highest proportion of epilepsy as a phenotypic component was observed in patients with del1p36 (OMIM #607872; 6/9 patients) and del1q21.1 (OMIM #612474; 6/15 patients). Conclusions: Our data support the clinical utility of CNV testing in patients with epilepsy accompanied by additional neurodevelopmental or dysmorphic features, in line with current diagnostic guidelines. The epilepsy-plus phenotype may help clinicians identify patients who are most likely to benefit from CNV analysis.