minus. (b) Cell from the same individual after hybridization with probes for 9p, 9q, 17q, and 17 centromere (control probe; aqua signals). Note additional 9q signal on the end of 1p. The mother carries a reciprocal translocation between chromosomes 1 and 9. (Courtesy of Emory Genetics Laboratory, Atlanta, GA)

Some abnormalities detected by this assay fall into categories of well-described deletion or duplication syndromes. Other cases may represent unique situations in which the abnormality consists of a derivative chromosome containing imbalances from two different chromosomal segments. The clinical literature regarding the phenotypes associated with small subtelomeric imbalances is rapidly expanding; however, it must be remembered that this assay does not determine the size of the imbalance. Two individuals with identical abnormal hybridization patterns may have very different phenotypes due to differences in the extent of genetic imbalance.

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