A loss of synaptic integrity leads to cognitive impairment in the AD brain (Coleman and Yao, 2003; Gylys et al., 2004), and PSD-95 as a neuronal scaffolding protein (Niethammer et al., 1996) is known to influence synapse maturation and regulate synaptic plasticity in the neuronal network (Kennedy, 2000; Elias et al., 2006). Here, DLG4 is linked to Alzheimer disease.