GRIN2A and bipolar disorder: [19–21] Another CNV on 16p13.2 containing GRIN2A, a gene encoding the GluN2A subunit of the N-methyl-D-aspartate receptor (NMDAR) and previously associated with various epilepsy phenotypes [22, 23], is one of the very few loci that is recurrently associated with various mental disorders, i.e. bipolar disorders [24] and schizophrenia [25].