Molecular Profiling of Polish Pediatric Patients with Epilepsy: A Single-Center Diagnostic Experience Using Next-Generation Sequencing

<b>Introduction:</b> Epilepsy syndromes show marked clinical and genetic heterogeneity, with numerous functionally diverse genes involved in their etiology. Next-generation sequencing (NGS) has facilitated the identification of many monogenic epilepsy syndromes and enables earlier, more accurate diagnosis in pediatric patients. <b>Materials and Methods:</b> This study analyzes the molecular profiles of 87 pediatric patients with various forms of epilepsy in whom pathogenic or likely pathogenic variants were identified. Next-generation sequencing (NGS) using multi-gene epilepsy panels or whole-exome sequencing (WES) was performed. <b>Results:</b> A total of 88 pathogenic or likely pathogenic variants were detected in 48 epilepsy-related genes; 30 variants occurred de novo. <i>SCN1A</i> and <i>KCNQ2</i> were the most frequent contributors (12.6% and 9.2%, respectively). The highest percentage of positive diagnoses (48%) was observed in patients with developmental and epileptic encephalopathy (DEE), with variants identified in genes including <i>ALG13</i>, <i>ATP1A2</i>, <i>CACNA1A</i>, <i>CDKL5</i>, <i>CHD2</i>, <i>GABRG2</i>, <i>ITPA</i>, <i>KCNQ2</i>, <i>PCDH19</i>, <i>SCN1A</i>, <i>SCN2A</i>, <i>SCN3A</i>, <i>SCN8A</i>, <i>SMC1A</i>, <i>SPTAN1</i>, <i>STXBP1</i>, and <i>UBA5</i>. Pathogenic variants in <i>ANKRD11</i> were found in four patients with KBG syndrome, while other genes appeared sporadically. <b>Conclusions:</b> Targeted massively parallel sequencing is an effective diagnostic tool for pediatric epilepsy. The presence of numerous single-case findings highlights the high genetic heterogeneity of epilepsy. This approach enabled more precise diagnoses that would not have been achieved through clinical evaluation alone, underscoring the importance of genetic testing for prognosis and treatment planning in pediatric patients with unexplained epilepsy.