Exploring gene-phenotype relationships in GRIN-related neurodevelopmental disorders

The GRIN family is implicated in neurological disorders, such as global developmental delay (GDD) and epilepsy. We reviewed 31 patients with GRIN-related neurodevelopmental disorders at Seoul National University Hospital; all exhibited profound GDD, with 58.1% unable to walk independently and 74.2% unable to speak meaningful words. In a pooled analysis with the GRIN portal data ( https://grin-portal.broadinstitute.org/ ), patients with missense or in-frame variants had significantly higher rates of profound GDD (74.3% vs. 30.4%, p < 0.001) and movement disorders (69.0% vs. 41.4%, p < 0.01) than those with protein-truncating variants. Furthermore, missense or in-frame variants in the M3 and M4 helices of the transmembrane domain were significantly associated with profound GDD (M3 helix: adjusted odds ratio [aOR] 8.48; 95% confidence interval [CI] 2.79-25.76; M4 helix: aOR 3.14; 95% CI 1.39-7.09) compared to those in other domains. Our findings highlight the importance of detailed variant characterization to inform personalized treatment strategies.