GRIN2A and neurodevelopmental disorder: While the gene encoding for the GluN2B subunit is the most frequently de novo mutated GRIN gene in psychiatric and neurodevelopmental disorders, de novo mutations of GRIN1 and GRIN2A genes encoding for GluN1 and GluN2A are less frequent and, interestingly, in GRIN2C, GRIN3A, and GRIN3B, only rare truncating mutations affecting both healthy individuals and patients suffering from neurodevelopmental disorders have been reported (Tarabeux et al., 2011; Soto et al., 2014).