Moreover, the decreased expression of GRIK2 and glutamate receptor metabotropic 4 (GRM4) and the increased expression of GRM1 were found in CFS subjects compared to non-fatigue controls in this study, implicating glutamate signaling dysfunction in the process of chronic fatigue (8). The gene discussed is GRIK2; the disease is myalgic encephalomeyelitis/chronic fatigue syndrome.