CDKN2A and glioblastoma: Other common molecular genetic alterations associated with GBM: TERT gene mutations, phosphatase and tensin homolog (PTEN) mutations, epidermal growth factor receptor (EGFR) amplification, cyclin-dependent kinase 4 (CDK4) amplifications, and cyclin-dependent kinase inhibitor 2 A (CDKN2-A) homozygous deletion [19].