PTEN and Macrocephaly: Also, cases of extreme macrocephaly in ASD have been correlated to mutations in the gene phosphatase and tensin homolog (PTEN) [17,18], making its testing the standard genetic screening for patients who present with autism and macrocephaly [19,20], although mutations account for only a small subset of the cases and have not been clearly correlated with susceptibility to seizures in ASD [21].