PTEN and astrocytoma (excluding glioblastoma): Genetic mutational studies in 83 canine gliomas (46 oligodendrogliomas, 31 astrocytomas, and 6 undefined gliomas) demonstrated PTEN homozygous deletion and arm-level aneuploidy in PTEN regions in 3% and 14% of cases, respectively [33], while additional investigations reported copy number alterations in PTEN in 15% of canine gliomas [19].