We selected SNPs with p<10−3 (Supplementary Table 2) to assess potential gene ontology enrichment using the online database ToppGene (see Methods). One biological process gene ontology category, response to drug, was significantly overrepresented. Eight molecular function categories were enriched. Several of these were very closely related – e.g., ionotropic glutamate receptor activity, extracellular-glutamate-gated ion channel activity, glutamate receptor activity, and excitatory extracellular ligand-gated ion channel activity – and were each populated by the same five glutamate-related genes: GRIN2A, GRIN2C, GRID1, GRIA1, and GRIA4. Each of these genes encodes a glutamate receptor. In addition, a number of cellular component categories related to neural function were statistically overrepresented. All enriched categories are detailed in Table 2.
