Pathogenic de novo variants on the GRIN2B gene, which encodes the GluN2B subunit of NMDARs, have been linked to developmental delay and intellectual disability of variable severity with (OMIM accession no. 613970) or without (OMIM accession no. 616139) early onset seizures (Lemke et al., 2014; Swanger et al., 2016; Platzer et al., 2017; Platzer and Lemke, 2018; Benke et al., 2021). The gene discussed is GRIN2B; the disease is Global developmental delay.