The both the structural and numeric aberrations

The in
situ hybridization techniques is mainly use to detect a certain DNA or RNA
sequences Jones, 2015. These techniques utilize the probes to detect the
sequences of DNA or RNA rather than using antibodies Jones, 2015. “In situ”
is the detection of site where the DNA or RNA is located on the tissue section
or cell Jones, 2015. In situ hybridization was first performed with a
radioisotope-labelled probes then followed by autoradiography in the late 1960s
Cheng et al., 2017. Then in 1980s, in situ hybridization were upgraded with the
use of direct labelled DNA probes with fluorophores that is complementary to a specific
DNA sequences Cheng et al., 2017. Today, the latest in situ hybridization
techniques are fluorescence in situ hybridization (FISH). FISH is an advance
techniques that have been greatly improved in terms of its resolution,
specificity and sensitivity Cheng et al., 2017.

            Cheng et al., (2017) stated that “FISH
involves the use of fragments of DNA (probes) binding to interphase chromosome
of cytology specimens or paraffin embedded tissue sections”. Then, Mekki J.S.,
(2016) stated that “the use of FISH allowed the identification of both the
structural and numeric aberrations that specify certain hematopoietic and
non-hematopoietic malignancies”. The technique of FISH can be use on an air dried
cytological preparation, FFPETS, frozen section, and fresh tissues, it can
detect molecular abnormalities of either cancer or tumours, and it also can be
use in the detection of genetic and chromosomal numeric abnormalities Mekki,
2016.

            In FISH, it mainly targeting the
nuclear DNA of either the interphase cells or of the metaphase chromosome
affixed to a microscope slide Bishop, 2010. The basic elements needed in FISH
are target sequence and DNA probe Bishop, 2010. Before hybridization process,
the DNA probe can be labelled either directly via the fluorophore or indirectly
with hapten (a small molecule that can only induce immune response when
attached a large carrier such as protein Shakoori, 2017) Bishop, 2010.
After that, the labelled probe and the target DNA undergo denaturation to create
a single-stranded DNA Bishop, 2010. The single stranded DNA of labelled probe
and target DNA are then combined which allow the annealing process of complementary
DNA sequences Bishop, 2010. The indirectly labelled probe required an additional
step for visualization of the non-fluorescent hapten that uses an enzymatic or
immunological detection system Bishop, 2010. However, the probe that are
labelled directly can be evaluated directly by fluorescence microscopy
Bishop, 2010.

              Among the
advantages of FISH technique are it allowed the identification of a specific
chromosome abnormalities, monitoring the progression of disease, and monitoring
the success of bone marrow transplantation Bishop,
2010.
The limitations of FISH are it cannot serve as a screening test for chromosomal
rearrangements, can only detect known genetic aberrations, depend on combined
fluorochrome probes, and FISH analysis are restricted to the targeted
chromosome or chromosomal sub-region Bishop,
2010.