APP and fragile X syndrome: A study by Westmark et al. found a 1.7-fold increase APP expression in the Fmr1 KO mouse versus WT using western blot analysis and showed that the genetic knockdown of one APP allele in the Fmr1 KO mouse rescued the FXS phenotypes including anxiety, seizures, mGLuR-LTD, and the ratio of mature versus immature dendritic spines [163].