Autism Spectrum Disorder (ASD) is a developmental disorder characterized by symptoms such as altered social interaction, restricted communication, and stereotyped behavior. There are many types of autism caused by different genetic defects. The study investigates the role of mutations in the gene Pten could underlie some cases of ASD. About 20% of autistic children also have larger heads or macrocephaly. Four recent studies searched for mutations in the Pten gene in patients with ASD and macrocephaly. They found that 5 to 17% of these patients do have mutations in the Pten gene. This correlative evidence alone does not support the conclusion that these mutations are the cause of ASD in these individuals. However, mutant mice lacking the Pten gene in certain brain regions have been engineered. These mice have macrocephaly and deficits in social behavior supporting the idea that Pten mutations may cause some forms of ASD. This study hopes to close the gap between what is known about human Pten mutations and mice in which Pten has been deleted in the brain. To do this, the researchers will introduce the Pten mutations that have been identified in human patients into the mouse. An advantage of doing this in the mouse is that they are able to perform experiments to record the activity in individual neurons. The research team has found that turning off or turning down activity of the Pten gene results in increased growth and abnormal activity of neurons. This study examines whether mutations found in human patients have similar effects on neurons as turning off or turning down Pten. If it is established that mice in which Pten is manipulated can serve as a model for human ASD experimental treatments can be tried on the mouse model. Understanding the primary effect of Pten mutations at the cellular level may lead to finding treatments that correct these cellular defects that are at the very heart of the dysfunctional autistic brain.