GRIN1 and polymicrogyria: To investigate whether polymicrogyria-associated GRIN1 mutations influence NMDA receptor function in vitro we undertook site-directed mutagenesis to introduce five of the GRIN1 mutations (p.Tyr647Cys, p.Arg659Trp, p.Asn674Ile, p.Asp789Asn and p.Arg794Gln) into cDNA encoding human GluN1.