Detection of copy number variations in epilepsy using exome data

Area of Science:

• Genetics
• Neurology
• Genomic Medicine

Background:

• Epilepsies are common neurological disorders with significant genetic contributions.
• Copy number variations (CNVs) are increasingly recognized as a key cause of genetic epilepsy.
• Whole-exome sequencing (WES) is a powerful tool for identifying genetic variations, including CNVs.

Purpose of the Study:

• To evaluate the utility of WES for detecting pathogenic CNVs in families with epilepsy.
• To compare the diagnostic yield of WES-based CNV detection against conventional methods.
• To assess the ability of WES to detect small CNVs (<10 kb).

Main Methods:

• Analyzed 294 epilepsy families using whole-exome sequencing (WES) data.
• Focused on 168 families lacking causative single nucleotide variants in known epilepsy genes.
• Utilized two distinct CNV detection tools on WES data for validation.

Main Results:

• Confirmed 18 pathogenic CNVs in the studied cohort.
• Identified 4 CNVs of unknown clinical significance at chr15q11.2.
• Successfully detected small CNVs (<10 kb) and identified cases missed by one CNV tool, highlighting the benefit of using multiple tools.

Conclusions:

• WES-based CNV detection offers a high diagnostic yield (10.7%) for epilepsy, comparable to or exceeding conventional microarray analysis.
• WES can identify small CNVs, expanding diagnostic capabilities.
• Employing multiple CNV detection tools with WES data is recommended to maximize diagnostic accuracy in epilepsy genetic testing.