Chromosomal aberrations refer to changes in chromosome structure or number. The document discusses various types of structural aberrations like deletions, duplications, inversions, and translocations, and numerical aberrations involving changes in ploidy. Karyotype analysis involves staining and arranging chromosomes to identify aberrations. Abnormal karyotypes can lead to diseases like Down syndrome, Patau syndrome, and Cri du chat syndrome. The normal human karyotype contains 22 pairs of autosomes and an XX or XY sex chromosome complement.

1. PADMASHREE INSTITUTE OF
MANEGMENTAND SCIENCE.
Seminar topic on;
 HUMAN CHROMOSOMAL ABERRATIONS,
Karyotype analysis
Presented by;
Shylesh murthy I .A
1st yr Msc biotechnology
PIMS

2. HISTORY
 Chromosomes were first observed in plants, investigation of
human karyotype took many years to settle .
 In 1912 Hans von Winiwarter reported 47 chromosomes in
spermatogonia and 48 in oogonia concluding XX/XO sex
determination mechanism .
 Painter in 1922 was not certain and revised his opinion from
46 to 48 chromosomes . He correctly insisted on human having
XX/XY chromosome system

3. Human ChromosomalAberration
 Change in the structure and number of
chromosomes are called chromosomal aberration.
 Its off 2 types 1. Structural and numerical
abnormalites
 There are 4 types of structural abnormalites
1. Deletion
2. Duplication
3. Inversion
4. Translocation

4. Deletion
 In this type a segment of chromosome is lost
its off 2 type
A.Terminal ;-
B. Inter calery ;-
A B C D E F G
A B C D E F G

5. Example;- Cri-du-chat syndrome
In human babies deletion of a segment of a chromosome
at Number 5 causes Cri-du-chat syndrome
Symptoms ;- it cries Like cat and its mentally retarded with
small head

6. Duplication
 Where a segment is get repeated .Hence a set of
genes is present inn double doses

Normal chromosome
Chromosome with duplication
A B C D E F G H
A B C D E F G H G H

7.  During meiosis ,the duplicated segment forms a
Loop
 These duplication produces ‘POSITION EFFECT’
 Example;- Down’s syndrome
Here It is a case of 21st trisomy ,ie an extra
chromosome of the 21st pair is present .hence there are
47 chromosomes (2n+1) instead of 46. formally this
condition was known as mangolism.
Symptoms ;- The diseased person has a
characteristic fold of the eye called epicanthus.
 The eyes are small ,skull is large .

9. INVERSION
 Where the segment of the chromosome breaks
and rewinds in reverse order .
 In inversion there is no loss or gain of genes ,but
the genes are arranged in reverse order
 It is of 2 types ;- 1. pericentric
2. paracentric

10. 1. Pericentiric ;- in pericentic the centromere is included
in the inverted segment
2. Para centric ;- here the centromere is not included in the
inverted segment


11.  The chromosome with inverted segment produces an
inversion loop
 These iversion loop prevents crossing over
 It brings about the position effect

12. Translocation
 Where non homologous chromosome exchange
segments
 These translocation produces the Cross-shaped
structure
A B C D 5 6 7 8
1 2 3 4 E F G H
 Example ;- chroinic myeloid leukaemia(commonly
in male Than females)

13. Here the translocatin takes place
between
9th and 22nd chromosomes
Symptoms ;-
1. Enlarged spleen and
liver.
2. Mild fever and night
sweats
3. Increase in bone marrow
4. Bone pain

14. Variation in chromosome number
(ploidy)
EUPLOIDY ANEUPLOIDY
POLYIPLOIDY
( 3n ,4n ,5n)
HAPLOIDY
(n)
DIPLOIDY
(2n)
Nullisomy
( 2n-2)
Monosomy
( 2 n-1)
Polysomy
(2n+1 or
2n+2)

15. Karyotype
1. Nageli observed in plants in 1842.
2. Flemings observed in animals in 1882
3. Chromosomes arranged based on there shape ,size and
structure called karyotype
4. These karyotype of a species are represented by diagram
called IDIOGRAM

17.  Karyotypes can be used for many purposes as study of
chromosomal aberrations
 The study of karyotypes is important for cell biology
and genetics and the results may be used in evolutionary
biology and genetics
 The study of karyotypes is easily made possible by
staining .usually ,a suitable dye such as Giemsa ,is applied
after the cells have been arrested during cell division .

18. typesofbanding
 G banding
 R banding
 C banding
 Q banding
 T banding

19. G banding is obtained with giemsa stain and following digestion
of chromosomes is carried out by trypsin.darkly stained regions are
known as heterochromatin and lightly stained regions are known as
euchromatin.

20. R banding is the reverse of G banding ..the lightly
stained regions are euchromatin and darkly stained
regions are heterochromatin

21. C banding is also obtained with giemsa stain .it is used for
centromere staining

22. Q banding is a fluoroscent pattern obtained
using Quinacrine for staining . Pattern is similar to G
banding.

23. T banding is also obtained by giemsa staining and it is
carried out for visualization of telomeres.
Silver staining stains the nucleolar organization region associated
with proteins .

24. Example ;-
GTG Banding
G = G banding T = trypsin for
Pretreatment
G = Stain used(geimsa)

25.  The normal human karyotypes contain 22 pairs of
autosomal chromosomes and one pair of sex chromosomes
[allosomes].
 Normal karyotype for females contain two X
chromosomes[XX]
 Normal karyotype for male contain one X and Y
chromosome[XY]
 Any variation from the standard karyotype may lead to
developmental abnormalities .
NORMALHUMANKARYOTYPE

26. Abnormalhumankaryotype
 Chromosome abnormalities can be numerical as in the
presence of extra or missing X chromosome .
 Numerical abnormalities are termed as aneuploidy .it
occurs as a result of nondisjunction during meiosis in the
formation of gametes
 Common numerical abnormality is trisomy of 21st
chromosome .
 Structural abberations occur from errors in homologous
recombination .

27. Chromosomal abnormalitiesthatleadtodiseasein
humansinclude
 Downs syndrome
 Patau syndrome
 Cri du chat syndrome
 Klienfelters syndrome
 Turner syndrome

28. Trisomy 13 or D-trisomy (Patau syndrome)
Trisomy 18 or E-trisomy (Edwardsyndrome)
Trisomy 21 or G-trisomy (Down syndrome)

29.  1st described by Bartholin (1657) & redefined
by Patau (1960).
 This is present in both male and females .
Chromosomal complement: 47,XX,+13 (female)
or 47,XY,+13 (male)
 Symptoms ;- Mental deficiency
Low birth weight
Abnormal development
of frontal lobe

30. Malformed ears

33. References ; Biology DR SUDAKAR RAO-
INTERNET SOURCES

34. .Thankyou ……….