PSEN1 and Alzheimer disease: Genes altered only in APP/PS1, but not GFAP mutation models, relative to humans with AD, could reflect APP/PSEN1 actions upstream of astrocyte activation and some of the highly interactive genes only found in the APP/PS1 model were: SYN1, GRIA1, GRIA2, BDNF, GAD2, HPCA, PPP2CA, CACNG3, and NRXN3 (Fig 3C).