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Clinical Vignettes
Vignette 2: The Power of FISH
Here are examples of how FISH technology assists in interpreting array CGH results. Note that in each example, the array CGH finding is identical, but the FISH results are completely different.
Example 1: Abnormal microarray showing DNA dosage gain on chromosome 17p11.2.
FISH analyses of both interphase and metaphase cells demonstrate a gain (duplication) of the red probe used to represent the region of DNA dosage gain on the microarray (Figure 1). Interphase FISH clearly demonstrates three distinct signals. Metaphase FISH consistently demonstrates one red signal with greater intensity for all cells analyzed, signifying a duplication on chromosome 17p. The green signals represent control FISH probes for the subtelomeric long arm of chromosome 17.
Example 2: Abnormal microarray showing DNA dosage gain on chromosome 17p11.2.
FISH analyses of both interphase and metaphase cells demonstrate a gain (duplication) of the red probe used to represent the region of DNA dosage gain on the microarray (Figure 2). Interphase FISH clearly demonstrates three distinct signals. Metaphase FISH demonstrates two normal 17 chromosomes in addition to a marker chromosome 17p (also called a derivative 17p). The green signals represent control FISH probes for the subtelomeric long arm of chromosome 17.
