OCNDS is considered as linked to de novo mutations in one allele of the CSNK2A1 gene as revealed by whole exome sequencing (Okur et al., 2016; Akahira-Azuma et al., 2018; Chiu et al., 2018; Owen et al., 2018; Nakashima et al., 2019; Xu et al., 2020). Here, CSNK2A1 is linked to Okur-Chung neurodevelopmental syndrome.