PTEN and brain neoplasm: Moreover, an increased risk of several different brain tumor types is observed in certain tumor syndromes, such as Cowden syndrome associated with meningiomas and gangliocytomas, neurofibromatosis type 2 associated with schwannomas and meningiomas, and familial adenomatous polyposis associated with gliomas and medulloblastomas [5], linking germline variants in PTEN, NF2, and APC to predisposition to a variety of brain tumors.