Investigation of MMAC/PTEN gene mutations and protein expression in low grade gliomas.

The MMAC/PTEN tumor suppressor gene has an essential biological role in the formation of glioblastomas. It is known that there are variations in genetic alterations in tumors that develop in patients with different ethnic backgrounds; thus, we aimed to evaluate the incidence of MMAC/PTEN mutations and protein expression among various low grade gliomas of Turkish patients. We investigated 28 low grade gliomas for mutations of the MMAC/PTEN gene using single strand conformational polymorphism method followed by DNA sequencing. Additionally, the level of MMAC/PTEN protein expression in the tissues of 26 tumors was assessed by immunohistochemistry. In our investigation, MMAC/PTEN mutations were detected in 2 of 28 tumors (7.14%). One novel sequence variant G --> A transition at codon 159 was identified. This missense variation was a result of an alteration from AGG (Arginine) to AAG (Lysine). Moreover, it was observed that MMAC/PTEN protein expression was reduced to 73.08% of tumors. In conclusion, reduced MMAC/PTEN expression by genetic and/or epigenetic mechanisms in low grade gliomas might be associated with glioma tumorigenesis.