PTEN and glioblastoma: Also, deletion of CDKN2A/B (32.7%), deletion of PTEN locus (37.3%), amplification of the EGFR locus (38.2%), amplification of chromosomal regions 4q12 (10%), 12q13 (8.1%), and 12q15 (6.3%), deletion of 17p13 (15.4%), gain of chromosome 7 (22%), and loss of chromosome 10 (46%) were common in glioblastoma specimens.