Genomic structure of GRIK2 and locations of microsatellites and SNPs. The relative positions of nine microsatellites chosen using the Human Genome Database and the UCSC Genome Browser are shown above a bar, oriented from centromere (cen) to telomere (tel), representing the chromosome 6q16.3 region containing GRIK2 [18, 33]. The GRIK2 gene, comprising 17 exons (numbered) is expanded below the bar, and the region from exon 11 through the 3'UTR is further expanded below. The annotation of the 3'UTR region of GRIK2 in human genome databases is incomplete, indicating only a shorter transcript associated with use of a polyadenylation signal upstream from the TAA repeat. Data from  indicate that two polyadenyation signals may be used, producing either a shorter mRNA, without the TAA repeat, or a longer mRNA that contains it. Coding sequences are shown in dark blue and UTRs are shown in light blue, with introns shown as a thin black bar. The locations of relevant microsatellites and SNPs are denoted by downward and upward-pointing triangles, respectively. SNPs located in the GRIK2 gene are denoted by letter: a: rs2852565, b: rs2786251, c: rs6922753, d: rs2518283, e: rs2243355, f: rs3213607, g: rs2227283, h: rs2852620, i: rs1034254, j: rs12198351, k: rs28383483, l: rs28383484. The last polymorphism is located at the edge of the region of extended homology with rodent mRNAs (see Figure 2) and may lie either at the extreme end of the human 3'UTR or immediately outside of it.