The document discusses genomic mapping via fluorescence in situ hybridization (FISH), describing its principles, procedures, types, advantages, and disadvantages. FISH is used to identify and visualize the arrangement of genes or DNA sequences on chromosomes, particularly useful for detecting chromosomal abnormalities. Its applications include monitoring therapy effects and identifying gene deletions or amplifications, despite limitations in sensitivity and the ability to assess multiple abnormalities simultaneously.

1. GENOMIC
MAPPING:FISH(Fluorescent
in situ hybridization )
Submitted by-
Uttaran Modhukalya
M.Sc 2nd semester
Brahmaputra college

2. CONTENT
• INTRODUCTION
• PRINCIPLE
• PROCEDURE
• TYPES OF FISH
• ADVANTAGE
• DISADVANTAGE

3. INTRODUCTION
• Genomic mapping is a graphic representation of the
arrangement of genes or DNA sequences on chromosome &
used to identify and record the location of gene & distances
between genes on chromosome.
• There are mainly two kinds of genome maps are known :
1.Genetic or linkage maps &
2. Physical maps
• Where Physical map provides detail of the actual physical
distance between genetic markers, as well as the exact
location of genes.
• An example of Physical mapping is FISH. FISH is a powerful
technique for detecting RNA or DNA sequences in cells,
tissues & tumors.

4. PRINCIPLE
• The basic elements of FISH are a DNA probe and a target
sequence.
• Before hybridization the DNA probe is labelled indirectly
with a hapten (left panel) or directly labelled via the
incorporation of a fluorophore (right panel).
• The labeled probe and the target DNA are denatured.
• Combining the denatured probe and target allows the
annealing of complementary DNA sequences.
• If the probe has been labelled indirectly, an extra step is
required for visualization of the non-fluorescent hapten that
uses an enzymatic or immunological detection system.
Finally, the signals are evaluated by fluorescence microscopy.

6. PROCEDURE
• Preparation of the fluorescent probes
• Denaturation of the probe and the target
• Hybridization of the probe and the target
• Detection

7. PROCEDURE
Preparation of the fluorescent probes

11. TYPES OF FISH
• Q-FISH
• Fusion-Signal FISH
• Immuno-FISH
• M-FISH
• Multilocus or ML-FISH

12. ADVANTAGE
• Rapid technique and large number of cells can be
scored in a short period.
• Efficiency of Hybridization and deletion is high.
• Sensitivity and specificity is high. Cytogenetic
data can be obtained from non-dividing or
terminally differentiated cells.
• Cytogenetic data can be obtained from poor
samples that contain too few cells for routine
cytogenetic analysis.

13. DISADVANTAGE
• Restricted to those abnormalities that can be
detected with currently available probe.
• Only one or a few abnormalities can be assessed
simultaneously.
• Due to Failure to detect signal FISH is higher
sensitive for trisomy but less sensitive foe detecting
chromosome loss or deletion.
• Cytogenetic data can be obtained only for the target
chromosomes thus FISH is not a good screening
tool for cytogenetically heterogeneous disease.

14. APPLICATIONS
• Detection of numerical and structural Chromosomal
abnormality.
• Identification of marker chromosomes. Monitoring
the effect of therapy.
• Detection of early relapse or minimal residual
diseases.
• Detection gene deletion and gene amplification.

15. REFERENCE
• Slideshare Presentation
• Shomu’s Biology
• Internet
• YouTube