The metabotropic glutamate receptor 5 (mGluR5) is an important regulator of excitatory (glutamate) and inhibitory (γ-aminobutyric acid, GABA) pathways [1, 2] and atypicalities in its expression are associated with a number of neurological and psychiatric conditions including epilepsy [3], anxiety [4] and autism spectrum disorder (ASD) [5]. Here, GRM5 is linked to autism spectrum disorder.