Molecular cytogenetic evaluation of a canine histiocytic malignancy using aCGH and FISH. A. Example of whole genome aCGH profile of a HS in a five year old female FCR. Log2 ratios representing thresholds of genomic gain and loss are indicated by horizontal bars above (green line) and below (red line) the midline (orange line), which represents normal copy number. The chromosome copy number status line for the tumor appears as an orange overlay of the center-line when there is a normal copy number, and as either green (gain) or red (loss) in the regions where genomic imbalances were apparent, as determined by the aCGH Smooth algorithm . The aCGH profile is annotated with the clone address of nine BAC clones from the 1 Mb array that were used in subsequent FISH analysis of this case. Three of these nine clones have been shown previously to contain the full coding sequence of a key cancer-associated gene (CDKN2A, RB1, PTEN) . The color of the text denotes the fluorochrome with which the BAC clone was labeled. B, C Targeted FISH analysis of tumor metaphase chromosome spreads from the same case using nine differentially labeled BAC clones (highlighted in A) combined in two separate groups. The modal copy number for each clone is indicated. D. Summary of copy number data of all nine loci evaluated by FISH analysis of at least 30 tumor interphase nuclei or metaphase spreads. The aCGH copy number status of these regions (gain, loss, balance) are indicated, demonstrating concordance between FISH data and aCGH data.