Fluorescence In Situ Hybridization (FISH)

Fluorescence in situ hybridization (FISH) is the use of fluorochrome tagged probes that bind only to the parts of a chromosome with complementary sequences. It can be used to identify chromosome segments, to correlate chromosome structures with gene locations, to reveal cryptic abnormalities that are undetectable using standard banding techniques, and to analyze and describe complex rearrangements1.  


FISH analysis with sequence-specific DNA probes. WiCell's assays are performed by clinically certified cytogenetic technologists and reviewed by an ABMGG-certified director, with results typically available in 10-15 days.



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What it detects:

  • Genomic sequence of interest

    • Duplications or deletions >20Kb
    • >2% mosaicism (for example: cultures where >2 of 100 cells are trisomy 12)
    • Chromosomal location of genomic gains
    • Chromosome fusions (breakaparts)

What it doesn't detect:

  • Changes in regions other than the probe-specific sequence


WHEN TO USE:

  • To confirm findings and refine breakpoints detected by g-banded karyotyping
  • To confirm findings and localize genomic gains detected by microarray analysis
  • As a screen for microdeletions/duplications of known targets
  • As a screen for aneuploidies 
  • As a screen for subtle duplications of 1q and 20q
 

References:

1. McGowan-Jordan, J., Simons, A., & Schmid, M., (Eds.) (2016). An International System for Human Cytogenomic Nomenclature (2016). Basel, Switzerland: S. Karger Publishing.