Following the Gultekin criteria (1), we suggest that patients with unexplained psychiatric disorders should be tested for anti-mGluR5 encephalitis when there is at least one of the following abnormalities: CSF showing inflammatory changes (pleocytosis, oligoclonal bands, increased immunoglobulin content or increased protein content in the absence of measured immunoglobulin); MRI showing unilateral or bilateral temporal lobe abnormalities on T2 weighted images and EEG showing slow-or sharp-wave activity in one or both temporal lobes. This evidence concerns the gene GRM5 and viral encephalitis.