• Ying Ren, Wandong Hu, Zaifen Gao, Jianguo Shi, Yong Liu, and Hongwei Zhang.
• Epilepsy Center, Children's Hospital Affiliated to Shandong University, Jinan, China.
• Medicine (Baltimore). 2025 Jan 10; 104 (2): e41236e41236.

RationaleDevelopmental and epileptic encephalopathy (DEE) defines a group of severe and heterogeneous neurodevelopmental disorders. The voltage-gated potassium channel subfamily 2 voltage-gated potassium channel α subunit encoded by the KCNB1 gene is essential for neuronal excitability. Previous studies have shown that KCNB1 variants can cause DEE. Herein, we report the cases of 2 children with DEE caused by pathogenic variants in the KCNB1 gene. Trio whole-exome sequencing identified novel KCNB1 genotypes, c. 1160C > A and c.1012C > T, which had not been reported previously, in 2 unrelated patients.Patient ConcernsTwo children were admitted to our hospital for a detailed evaluation of frequent seizures. And both of these children have abnormal electroencephalogram and brain magnetic resonance imaging results, accompanied by developmental delay.DiagnosesA genetic study using trio-whole-exome sequencing confirmed the diagnosis of KCNB1-related developmental and epileptic encephalopathy.InterventionsBoth patients accepted the treatment of antiepileptic drugs. 1 patient had seizure remission with a combination of sodium valproate and lamotrigine, and the other was lost to follow-up.OutcomesTrio-whole-exome sequencing technology was used to determine the etiology of the 2 children with DEE.LessonsThis study confirmed that genetic testing provides a basis for the diagnosis of children with abnormal electroencephalogram and brain magnetic resonance imaging findings and developmental delay, and provides data supporting a future phenotype-genotype correlation study.Copyright © 2025 the Author(s). Published by Wolters Kluwer Health, Inc.

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