GRIA genes. This is the first time we are describing GRIA genes on this blog. GRIA genes, which include GRIA1, GRIA2, GRIA3, and GRIA4, encode the AMPA receptor, one of the two key channels in the process of glutamate neurotransmission. While GRIN genes, which encode the NMDA receptor, have been characterized much more extensively in the literature, GRIAs remain relatively under-characterized, even though their protein products are involved in a similar molecular process in the post-synapse in modulating excitatory synaptic transmission. Here, we provide a brief overview of the genetic and phenotypic range of GRIA-related disorders.