Other genes associated with fibromyalgia that regulate nociceptive and analgesic neuronal pathways are the TAAR1 receptor gene, the regulator of G protein signaling 4 gene (RGS4), the cannabinoid receptor 1 gene (CNR1), and the ionotropic glutamate receptor AMPA 4 gene (GRIA4) [65,67]. Here, GRIA4 is linked to fibromyalgia.