# A case of early epileptic encephalopathy caused by new mutation at W218C in KCNQ2 and review literature

## TL;DR

A new mutation in the KCNQ2 gene is linked to severe early-onset epileptic encephalopathy in a newborn, leading to poor neurological outcomes.

## Contribution

The study reports a novel KCNQ2 mutation (W218C) associated with severe clinical manifestations and poor prognosis in early-onset epileptic encephalopathy.

## Key findings

- The W218C mutation in KCNQ2 was identified as a harmful variant using in silico tools.
- The mutation is located in the S4S5 connection region of the protein and is linked to West syndrome and poor neurological outcomes.
- Whole exome sequencing provided critical genetic information for diagnosing neonatal epileptic encephalopathy.

## Abstract

Early-onset epileptic encephalopathy (EOEE) is mainly characterized by early refractory epileptic seizures in infants with progressive brain dysfunction, accompanied by complex causes (such as perinatal brain injury, structural brain malformations and genetic metabolic diseases). Early identification and etiological treatment are critical. It has been reported that mutations in Potassium Voltage-Gated Channel Subfamily Q Member 2 (KCNQ2) can result in EOEE. This study analyzed the genetic defects and clinical phenotypes of a newborn with early epileptic encephalopathy. Whole exome gene detection identified a novel heterozygous point mutation p. W218C in KCNQ2. The pathogenic variant was located in the protein's S4S5 connection region and was identified as a harmful mutation by silico tools. The child's clinical phenotype finally manifested as West syndrome during the follow-up. The mentioned variation may lead to severe clinical manifestations and poor neurological prognosis. Whole exome gene detection provides clinicians with more information on neonatal epileptic encephalopathy.

•Our findings identify a novel missense mutation at the W218C locus within the KCNQ2 gene, which is associated with severe clinical manifestations and unfavorable neurological outcomes.•These results provide valuable insights for clinical genetic counseling and offer novel perspectives for future investigations into the pathogenesis of this disorder.

Our findings identify a novel missense mutation at the W218C locus within the KCNQ2 gene, which is associated with severe clinical manifestations and unfavorable neurological outcomes.

These results provide valuable insights for clinical genetic counseling and offer novel perspectives for future investigations into the pathogenesis of this disorder.