Considering that a subset of individuals with ASD who presented macrocephaly had only one mutated Pten allele [9], [19], [20], not a complete knock-out as used in Kwon et al.[14], we used conditional Pten knock-out mice in which only one allele of Pten was selectively knocked-out in neurons to better resemble the genotype and phenotype of these patients without increasing significantly the risk or incidence of cancer which may obscure the outcomes. The gene discussed is PTEN; the disease is cancer.