Understanding the nomenclature of cytogenetics is very important in reporting patient FISH results correctly.
The ISCN "string" is the sentence that describes the cytogenetic findings in ISCN format.
For FISH, the generic "string" is as follows: Interphase FISH is Nuc ISH is (gene location X range of signals observed)(gene location X range of signals observed)[number of cells counted].
For example, for a HER2/neu assay in breast cancer, the ISCN string would be:
Interphase FISH is Nuc ISH is (DZ17 x 1-3)( x 3-8).