Fig. 2.

Representative FISH hybridizations performed on tissue microarrays. A. GBM with a normal disomic complement of 1p. Most cells have 2 green (1p32) and 2 red (1q42) signals. Some appear to have fewer than 2 copies because of the truncation artifact encountered in thin tissue sections (i.e., incomplete DNA complement in sectioned nuclei). Some signals are out of the plane of focus represented in the photograph. B. Pattern of 19q deletion in GBM showing 2 green (19p13) signals and 1 red (19q13.4) signal in most nuclei. C. Pattern of chromosome 10 deletion in a GBM. Only 1 green (PTEN) signal and 1 red (DMBT1) signal are detected in each nucleus, most likely representing either a large 10q deletion or the loss of an entire chromosome 10. D. Pattern of homozygous deletion of 9p21 (p16/CDKN2A) in a GBM. Only green signals from the centromeric probe are noted in the majority of nuclei. Signals from 9p21 (red) are almost entirely absent.