Several monogenic autism spectrum disorders have mutations leading to defects in the PI3K pathway, such as tuberous sclerosis (TS) [14], fragile X syndrome (FXS) [1, 15], neurofibromatosis 1 (NF1) [16], and brain disorders associated with phosphatase and tensin homolog (PTEN) mutations [17]. Here, PTEN is linked to fragile X syndrome.