PTEN GENE-MUTATIONS ARE SEEN IN HIGH-GRADE BUT NOT IN LOW-GRADE GLIOMAS

The PTEN gene, located on 10q23, has recently been implicated as a can didate tumor suppressor gene in brain, breast and prostate tumors. In the present study, 123 brain tumors, including various grades and hist ological types of gliomas occurring in children and adults, were analy zed for PTEN mutations by SSCP assay and sequencing. Mutations in the PTEN gene were found in 13 of 42 adult glioblastomas and 3 of 13 adult anaplastic astrocytomas, whereas none of the 21 low-grade adult gliom as or the 22 childhood gliomas of all grades showed mutations. The sin gle medulloblastoma with a mutation was a recurrent tumor that also po ssessed a p53 mutation. High-grade adult gliomas with PTEN mutations i ncluded cases that also contained gene amplification or p53 gene mutat ions, as well as cases that did not contain either of these abnormalit ies. There was no obvious relationship between presence of PTEN mutati on and survival; however, there was a tendency for PTEN mutations to o ccur in older age group patients. This analysis suggest that PTEN gene mutations are restricted to high-grade adult gliomas and that this ab normality is independent of the presence or absence of gene amplificat ion or p53 gene mutation in these tumors.