Supplementary Material for: Clinical Features of Okur-Chung Neurodevelopmental Syndrome: Case Report and Literature Review

<b><i>Introduction:</i></b> Autosomal dominant pathogenic variations in the <i>CSNK2A1</i> gene cause Okur-Chung neurodevelopmental syndrome (OCNDS). <b><i>Methods:</i></b> The proband and her parents were examined thoroughly and observed for any issues related to OCNDS. Furthermore, peripheral blood samples were collected from each subject for further investigations. Whole-exome sequencing identified a pathogenic variant in <i>CSNK2A1</i> (NM_001895: c.62G&gt;A, p.R21Q; rs1402734448). <b><i>Results:</i></b> The proband has global developmental delay, speech disorders, epilepsy, and behavioral issues. Despite the previously reported cases, she manifested both atonic and myoclonic seizures simultaneously. Lastly, we provide a review of the reported cases with OCNDS. <b><i>Discussion:</i></b> p.R21Q causes OCNDS. Further studies are highly recommended concerning this mutation to validate the results of this study and expand the knowledge regarding <i>CSNK2A1</i> and the phenotypic spectrum of OCNDS.