Golgi stain studies have found an overabundance of immature spines in both FMR1 KO mice (Comery et al., 1997; Galvez and Greenough, 2005; Mckinney et al., 2005) and FXS human tissue (Hinton et al., 1991; Wisniewski et al., 1991; Irwin et al., 2001). The gene discussed is FMR1; the disease is fragile X syndrome.