Polymorphisms in CACNA1A, CACNA1C, and CACNA1H Genes in Korean Pediatric Patients with Developmental Delay and Intellectual Disability: A Focus on Epilepsy Comorbidity

<b>Background:</b> Developmental delay and intellectual disability (DD/ID) are frequently accompanied by epilepsy, and growing evidence implicates variants in voltage-gated calcium channel genes in their pathogenesis. This study aimed to investigate the association of polymorphisms in <i>CACNA1A</i>, <i>CACNA1C</i>, and <i>CACNA1H</i> with DD/ID and epilepsy comorbidity in Korean children. <b>Methods:</b> We retrospectively analyzed 141 pediatric patients diagnosed with DD/ID who underwent whole-exome sequencing (WES) and were not found to have pathogenic monogenic variants. Nine single-nucleotide polymorphisms (SNPs) across <i>CACNA1A</i>, <i>CACNA1C</i>, and <i>CACNA1H</i> were selected based on functional annotation scores and prior literature. Genotype data were extracted from WES variant files, and allele and genotype frequencies were compared with control data from the gnomAD East Asian population and the Korean Reference Genome Database (KRGDB). Subgroup analyses were performed according to epilepsy comorbidity. <b>Results:</b> The <i>CACNA1A</i> rs16023 variant showed a significantly higher B allele frequency in DD/ID patients than in both control datasets and was also associated with epilepsy comorbidity. Genotype distribution analysis revealed that the BB genotype of rs16023 was more frequent in patients with epilepsy. <b>Conclusions:</b> The <i>CACNA1A</i> rs16023 variant may contribute to genetic susceptibility to DD/ID and epilepsy in Korean children, potentially through regulatory mechanisms. These findings support the relevance of calcium channel genes in neurodevelopmental disorders and highlight the importance of integrating functional annotation in variant prioritization.