In humans, germline mutations of PTEN cause a group of rare autosomal dominant syndromes (PTEN hamartoma tumor syndromes, PHTS), characterized by increased risk for specific malignancies (breast, thyroid, renal, and endometrial cancers) and neurodevelopmental disorders, such as autism and mental retardation [13,14,15]. Here, PTEN is linked to PTEN hamartoma tumor syndrome.