GRIK2 and early-onset autosomal dominant Alzheimer disease: Gene-based analyses implicated AGXT2 and CALN1 for VL, while analyses of protein-protein interactions implicated synaptic proteins previously associated with Alzheimer disease biology, SYT9 and NRXN1 for VSTM; ZFAND5, GRIK2, and ZC3H18 for VL; and PRLHR for paragraph recall.