Gliomas are the most common primary neoplasm of the central nervous system and can have strikingly different clinical behaviors and responses to therapy. Distinguishing between different subtypes is often less than perfect with significant inter-observer variability. Although attempts have been made to define clinical and histologic features that correlate with a favorable prognosis, none have been sufficiently reliable at predicting response to adjuvant chemotherapy. Deletions of the 1p36.32 region including the TP73 (tumor protein 73) gene and deletions of the 19q13.33 region including the GLTSCR1 and GLTSCR2 (glioma tumor suppressor candidate region genes 1 and 2) genes are frequently reported in cases of glial tumours. The most commonly used probe pairs are commercially available, targeting 1p36/1p25 and 19q13/19p13. The 1p36/1p25 probes are designed for copy number detection of 1p36 deletions or 1q25 region in neuroblastoma and gliomas.