PTEN and central nervous system cancer: However, these techniques are still in development.25,26 Mutations in alpha-thalassemia/mental retardation syndrome X-linked (ATRX) are a marker for astrocytic lineage in diffuse gliomas.27 Inactivation of the phosphatase and tensin homolog (PTEN) tumor suppressor gene on chromosome 10 leads to progression from low-grade to high-grade gliomas.28 EGFR amplification, over-expression, or presence of a mutation such as EGFRvIII is present in approximately 50% of GBMs.29,30 The presence of these mutations in GBM provides a target for biomarker development.