On the other hand, although some reports have identified low frequency of PTEN mutations in HGG [27,28], which is consistent with our results, since no mutation was identified in 34 tumors, a mutational rate in up to ~60% in high-grade astrocytomas has been detected in most of the previous studies [29,30,31]. This evidence concerns the gene PTEN and astrocytoma (excluding glioblastoma).