For example, DISC1 (Disrupted in Schizophrenia) regulates dendritic spine morphology via Rac1 (Hayashi-Takagi et al., 2010) and mutations in the cofilin kinase PAK3 lead to X-linked mental retardation and memory impairments (Allen et al., 1998). This evidence concerns the gene PAK3 and memory impairment.