GRIA2 and Neurodevelopmental delay: In contrast to GRIA2, GRIA3, and GRIA4, the identity of GRIA1 as an NDD-causing gene has yet to be established, and only three GRIA1 missense variants so far have been reported in NDD individuals (p.Ile627Thr, p.Ala636Thr, and p.Gly745Asp).14, 15, 16 Interestingly, the p.Ala636Thr variant has been recurrently identified in six unrelated individuals via WES or targeted GRIA1 sequencing in two large NDD cohorts.14