In agreement with previous reports (Fell et al., 2011, Fujioka et al., 2014, Linden et al., 2005, Morishima et al., 2005), we found no consistent evidence for altered anxiety in mice lacking either mGlu2 or mGlu3 alone, suggesting that deletion of just one of the two receptor subtypes is not sufficient to produce robust effects on anxiety-like behaviours. The gene discussed is GRM2; the disease is Anxiety.