The transcriptional E/I ratio, defined as the level of mRNA for DLG4, which encodes PSD-95, divided by the level of mRNA for GPHN, which encodes gephyrin, was significantly elevated in AD (P = 0.017, nonparametric Wilcoxon/Mann–Whitney U-test) (Fig. 6a). This evidence concerns the gene DLG4 and Alzheimer disease.