Chromogenic in situ hybridization CISH

A diagnostic method using fluorescence labeled DNA probes to detect and quantify the number complementary chromosomal sequences on a cellular resolution. A related technique that also allows assessment of gene amplifications, but without precise quantification of copy numbers is the chromogenic in situ hybridization (CISH). Here, instead of a fluorescent dye an enzyme that can generate a colored precipitate in the tissue samples is coupled to the DNA probe. 

Under such circumstances, the chromogenic in situ hybridization (CISH) technique has been attracting attention in recent years. It is a well-known technique and has already been approved for HER2 testing [15,16], There are two major CISH methods used in HER2... 

Recent literature also explored chromogenic in-situ hybridization (CISH) as a method of choice for detection of EGFR copy number in FFPE tissue. The results showed good correlation with FISH analysis, however chromosome 7 polysomy cannot be readily distinguished from EGFR amplification. The importance of distinguishing polysomy from gene amplification is still uncertain. 

Chromogenic in situ hybridization (CISH) is a recent methodology wherein the HER2/neu gene copies are detected by a silver reaction and visualized by light microscopy. A study that evaluated CISH on ThinPrep-processed hne-needle aspirate specimens found a good concordance between CISH performed on LBC specimens as compared to paraffin-embedded tissue specimens. 

Zhao J, Wu R, Au A, et al. Determination of HER2 gene amplification by chromogenic in situ hybridization (CISH) in archival breast carcinoma. Mod Pathol 2002, 35, 657-665. 

FISH, Fluorescence in situ hybridization CISH, chromogenic in situ hybridization (generally DAB as chromogen) SISH, silver in situ hybridization. 

Therefore, several methods have been investigated to detect HER2 gene ampHfi-cation including Southern blot analysis, polymerase chain reaction (PCR) and in situ hybridization (ISH) methodologies, such as fluorescence ISH (FISH) and chromogenic ISH (CISH). 

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