Cytogenetic techniques

cytogenetic techniques

1. Submitted To-Dr. Rupam Dutta
Dept. of Animal Biotechnology
Asst. Professor, CVSc Khanapara
Submitted By-
Dr. Anamika Mazumdar
PG 1st year
2020-VMK-04
CYTOGENETIC
TECHNIQUES

2. CYTOGENETICS:-
(CELLULAR GENETICS)
•Cytogenetics is the study of
chromosomes; their structure and
properties, chromosome behaviour
during cell division, their influence on
traits and factors which cause
changes in chromosomes.

3. CYTOGENETICS:
PRINCIPLE
•The basic principle is to examine and analyze all
chromosomes, observe for any chromosomal change, be
it structurally or numerically.
•Karyotyping of cancer cells remains the gold standard
since it provides a global analysis of the abnormalities
in the entire genome of a single cell. However
subsequent methodological advances in molecular
cytogenetics based on the principle of FISH that were
initiated in the early 1990s have greatly enhanced the
efficiency and accuracy of karyotype

4. TECHNIQUES
•1. Whole blood culture and
karyotyping.
•2. Banding techniques
•3. FISH (Fluorescence in situ
hybridization)
•4. Comparative Genomic
Hybridization (CGH)
•5. Spectral Karyotyping (SKY) and
multicolor FISH (M-FISH)

5. KARYOTYPING
•Karyotyping is the process of pairing and ordering all the
chromosomes of an organism, thus providing a genome-wide
snapshot of an individual’s chromosomes.
•Karyotype is an individual’s collection of chromosomes.
A perfectly symmetrical karyotype has all metacentric
chromosomes of the same size. They are known to be
primitive state from which more advanced asymmetrical
karyotype has evolved through structural changes.

6. How Karyotype predicts
disorders?

7. FISH
-Fluorescence in situ hybridization.
-It is a molecular cytogenetic technique that uses fluorescent
probes that bind to only those parts of chromosome with a high
degree of sequence complementarity.
-It is used to detect and localize the presence or absence of
specific DNA sequences on chromosomes
FISH is used for
studying
embryonic stem
cells

8. Spectral Karyotyping or
Multicolor FISH
•A simultaneous hybridization of different probes has led to
‘multicolor FISH’ experiments in which more than two
fluorescent dyes are used for probe detection
•Ability to analyze complex cases with multiple chromosomal
rearrangements, identification of marker chromosomes.

9. Comparative Genomic
Hybridization
•Technique that permits detection of chromosomal copy number changes
without the need for cell culturing.
•Overview of gains and losses through whole genome sequence.
•Aims to quickly and efficiently compare 2 genomic DNA samples arising from 2
sources.
•Relatively fast screening technique.
•Indicative of chromosomal regions important in pathogenesis.
STEPS-
1.Preparation of Metaphase
slides
2.Extraction of Test and
Reference DNA
3.Labelling and fragmentation
of Test and Reference DNA
4.Hybridisation
5.Use of Fluorescence
Microscopy & Digital Image
Analysis

10. Chromosome Banding
Techniques
•Bands-are identified as parts of chromosomes, clearly distinguishable from
its adjacent segments by appearing darker with banding techniques.
•It is a technique used in chromosome karyotyping to identify normal and
abnormal chromosomes for clinical and research purposes.
•A unique banding pattern is used to identify each chromosome and diagnose
chromosomal aberration, including chromosomal breakage, loss, duplication,
inversions etc.
•Always metaphase chromosomes whose size has condensed and whose
diameter is increased are used for chromosome banding studies after fixing
the stage.
-Heterochromatin region –dark
-Euchromatin region-light

11. TYPES:-
G-GIEMSA
Dark bands-AT rich bases
Light bands-GC rich bases
Q-QUINACRINE
Dark bands-AT rich bases
Light bands-GC rich bases
C-CONSTITUTIVE
HETEROCHROMATIN/CENTROMERE
R-REVERSE
Dark bands-GC rich bases
Light bands-AT rich bases