Contradicting previous studies reporting higher frequency of homozygous deletions of PTEN and CDKN2A genes in gliomas [18,34,41,42], in our study only PTEN heterozygous deletions were found, while genomic analyses of CDKN2A showed that 28 patients harboring this alterations: 71.4% presented heterozygous deletion against 28.6% showing homozygous deletions. The gene discussed is PTEN; the disease is central nervous system cancer.