GRM5 and fragile X syndrome: Results from ensuing pre-clinical work with animal models of FXS published in over 40 papers in the literature found reversal of numerous phenotypic features following pharmacological treatment with mGluR5 negative modulators in both the fly and mouse models [28–32] and following genetic reduction of mGluR5 activity in fmr1 knockout mice also heterozygous for knockout of the mGluR5 gene.