Clinical Report: Challenges of Dual CNV Results in DEE7 Case Study

Overview

This case report details a 1 year 5 months female diagnosed with DEE7 due to a de novo KCNQ2 deletion and concurrent chromosome 13 duplication. Early intervention led to complete seizure freedom and modest neurodevelopmental progress, emphasizing the importance of CNV analysis in epilepsy genetic testing.

Background

Developmental and epileptic encephalopathy 7 (DEE7) is a severe disorder linked to mutations in the KCNQ2 gene, which is crucial for neuronal excitability. Understanding the clinical implications of large deletions in KCNQ2 is vital, as they can lead to significant phenotypic variability and treatment responses. This case highlights the need for comprehensive genetic testing and early intervention in managing such complex cases.

Data Highlights

Trio-based whole-exome sequencing identified a ∼1.62 Mb de novo heterozygous deletion at chromosome 20q13.33 and a co-occurring ∼4.68 Mb duplication at chromosome 13q34.

Key Findings

• Patient exhibited frequent seizures starting at 7 days old, with severe global developmental delay.
• Electroencephalography showed slowed background activity with multifocal epileptiform discharges.
• Neurodevelopmental assessments indicated a Griffiths Developmental Quotient of 60.
• Early targeted treatment resulted in complete seizure freedom and modest developmental progress.
• CNV analysis is essential in genetic testing for epilepsy to inform prognosis and treatment.

Clinical Implications

This case underscores the importance of early genetic testing and intervention in patients with severe genotypes associated with DEE7. Clinicians should consider CNV analysis as part of the diagnostic process to optimize treatment strategies and improve outcomes.

Conclusion

The successful management of this DEE7 case illustrates the potential for positive clinical outcomes through early intervention and highlights the critical role of genetic analysis in understanding complex epilepsy cases.

Related Resources & Content

1. Acta Neuropathologica, 2023 -- Identification of a New NDEL1 Variant Linked to Lissencephaly Highlights the Unique Functions of NDE1 and NDEL1 in Nucleokinesis and Cortical Developmental Disorders
2. The Journal of Clinical Endocrinology & Metabolism, 2025 -- Phenotypic Associations with SOX9 Upstream Duplications: Advancements in Understanding Clinical Presentation and Diagnosis
3. Brain, 2025 -- Mutations in Nav1.2 Channels Impairing Rapid Inactivation Result in SCN2A Encephalopathy
4. Current practice in diagnostic genetic testing of the epilepsies - PMC, 2023 -- Current practice in diagnostic genetic testing of the epilepsies
5. Frontiers in Cardiovascular Medicine — Case Report: Two cases of recurrent syncope caused by KCNH2 gene mutation in congenital long QT syndrome
6. Neonatal developmental and epileptic encephalopathies. English version | Clinical Epileptology
7. Study Results | NCT04639310 | XEN496 (Ezogabine) in Children With KCNQ2 Developmental and Epileptic Encephalopathy
8. Current practice in diagnostic genetic testing of the epilepsies - PMC