It includes the overview about chromosomes and different chromosomal aberrations.

1. CHROMOSOMAL
ABERRATION

2. Cytogenetics
o Karyotype – microscopic examination of
chromosome
Main feature to identify and classify chromosomes
1. Size
2. Location of the centromere
3. Banding patterns

3. G-Banded Metaphase Chromosome

4. Chromosomal Aberration
o is substantial changes in
chromosome structure
o typically affect multiple
genes (loci)
o due to error in cell division
(non-disjunction of
chromosomes and
chromatids), maternal age
or environment

5. Relationship Between Age and Aneuploidy
 Older mothers more likely to produce aneuploid
eggs
 Trisomy 21
 Due to meiotic non-disjunction in during oocyte
maturation

6. Meiotic Nondisjunction Generates Aneuploidies
abnormal
gametes
Zygotic Ploidy Zygotic Ploidy

7. Types of Chromosomal Abnormalities
o aneuploidy
o polyploidy
Numerical
Abnormalities
Structural
Abnormalities
o deletion
o duplication
o inversion
o translocation

8. Numerical Abnormalities
o Aneuploidy
o Variation in the number of particular chromosomes within a set
1. Hyperploidy- gain of chromosome/s
• Trisomy- 2n + 1
• Double trisomy- 2n + 1 +1
• Tetrasomy- 2n + 2
2. Hypoploidy- loss of chromosome/s
• Monosomy- 2n –1
• Double monosomy- 2n –1-1
• Nullisomy- 2n-2
o Polyploidy
o Condition in which the cells have more than 2 homologous sets of chromosome
1. triploid (3n)
2. tetraploid (4n)
3. Pentaploid (5n)

10. o Aneuploidy of sex
chromosome
o Occurs in 1 in 500-1000
o Sterile
o No obvious facial
dysmorphy
o Narrower shoulders and
wider hips
Klinefelter Syndrome – 47, XXY

11. o Smaller testes and penis
o Decreased sexual
interest
o Weaker bones
o Lower energy
o Breast growth
o Less facial and body hair
o Reduced muscle tone
Klinefelter Syndrome – 47, XXY

12. o Aneuploidy of sex
chromosome
o Aggressive due to high
level of testosterone
(prone to violent wife
beating)
o Adult male could be
more impulsive and
emotionally immature
Jacob Syndrome – 47, XYY
“How to tell if your child
is a SERIAL KILLER?”

13. o occurs in 1 in 1000
o lanky, clumsy,
uncoordinated
o dyslexia – develop in
reading disorder
o problem in motor
coordination
o behavioral problems
o behavioral tantrums
o more impulsive
o emotionally immature
Jacob Syndrome – 47, XYY

14. Turner Syndrome – 47, X
o Aneuploidy of the sex
chromosome
o demonstrate visuospatial
deficits including poor
handwriting and likely
underdeveloped
arithmetic skills

15. Turner Syndrome – Monosomy 47, X
o Short stature
o Ovarian failure
o otitis media
o early OM in TS could
lead in dyslexia (reading
disorder)

16. Patau’s Syndrome - Trisomy 13
o Severe intellectual
disability
o Physical abnormalities in
in many parts of the
body
o Heart defects, brain and
spinal cord abnormalities

17. Patau’s Syndrome - Trisomy 13
o Very small or poorly
developed eyes
(micropthalmia)
o Extra fingers or toes
o Weak muscle tone
(hypotonia)

18. Edward’s Syndrome – Trisomy 18
o intestines protruding
outside the body
o intellectual disabilities
o delayed development
o feeding and breathing
difficulties

19. Edward’s Syndrome – Trisomy 18
o Arthrogryposis - a
muscle disorder that
causes multiple joint
contractures at birth

20. Down Syndrome - Trisomy 21
o physical growth delays
o severe degree of
intellectual disability
o short stature
o delayed mental and
social development
o Impulsive behavior
o Poor judgment
o Short attention span
o Slow learning

21. Down Syndrome - Trisomy 21
o Sleep apnea - sleep
disorder characterized
by pauses in breathing
or instances of shallow
or infrequent breathing
during sleep
o Dementia - decline in
mental ability severe
enough to interfere with
daily life, memory loss
o Hypothyroidism - under
active thyroid

22. Aneuploid Condition in Humans
Condition Frequency Syndrome Characteristics
Autosomal
Trisomy 21 1/800 Down Mental retardation, abnormal pattern
of palm creases,slanted eyes,
flattened face, short stature
Trisomy 18 1/6,000 Edward Mental and physical retardation,
facial abnormalities, extreme muscle
tone, early death
Trisomy 13 1/15,000 Patau Mental and physical retardation, wide
variety of defects in organs, large
triangular nose, early death
Sex Chromosome
XXY 1/1,000 (males) Klinefelter Sexual immaturity (no sperm), breast
swelling
XYY 1/1,000 (males) Jacob Tall
XXX 1/1,500 (females) Metafemale Tall and thin, menstrual irregularity
X0 1/1,500 (females) turner Short stature, webbed neck, sexualy
undeveloped

23. Effects of Nullisomics
• dwarf
• less tillering
• female fertile
• male sterile
• awnless
Nullisomics-Mutants of the Ear in
Wheat (Triticum aestivum)
Ear shape of the wild type (WT) and of
several mutants lacking single pairs of
chromosomes (nullisomics). Due to the
hexaploidy, the lack of a pair of
chromosomes is tolerated. The effects
are usually different though stunted
growth is usually one of them.

24. Polyploidy
- with more than 2 sets of genome
o most common in plants which are asexually propagated
and infrequent in animals
o for sexually reproducing organisms, sex chromosome
balance must be maintained
Detection:
• change in morphology
• change in fertility
• change in interspecific cross ability

25. Triploid Plants (3n)
Tetraploid Plants (4n)

26. Benefit of Odd Ploidy-Induced Sterility
 Seedless fruit
 watermelons and bananas
 asexually propagated by human via cuttings
 Seedless flowers
 Marigold flowering plants
 Prevention of cross pollination of transgenic
plants

27. Structural Abnormalities
Deletion
Duplication
Inversion
Translocation
Amount of genetic
information in the
chromosome can
change.
The genetic material
remains the same but
it is rearrange.

28. Deletion
o Loss of a region of chromosome
o A chromosomal deficiency occurs when a chromosome breaks
and a fragment is lost

29.  Phenotypic
consequences of
deficiency depends
on
 Size of the deletion
 Functions of the
genes deleted
 Phenotypic effect of
deletions usually
detrimental
Deficiencies
Interstitial
Terminal
Two types of deletion

30. Cri-du-chat Syndrome
o High-pitched cry
o intellectual disability
o delayed development
o small head size
o low birth weight
o weak muscle tone in
infant

31. DiGeorge Syndrome
o deletion in long arm of
chromosome #22
o congenital heart disease
o Cyanosis
o learning difficulties
o psychiatric disorders

32. Angelman Syndrome
o deletion in chromosome
#15
o uncontrolled laughter
o no speech development

33. Duplication
o A chromosomal duplication is usually caused by
abnormal events during recombination

34. Duplication
o Small duplications often
are not accompanied by a
phenotypic effect
o Large duplications
produce phenotypes
through imbalanced gene
dosage
o tend to be less
detrimental
o constitute a major force of
genome evolution.
Direct Inverted

35. Inversion
o A segment of chromosome that is flipped relative to that in the
homologue
o Two breaks in one chromosome
o The fragment generated rotates 180o and reinserts into the
chromosome
Pericentric -
involves p and q
arm
Paracentric -
involves only
one arm

36. Inversion
o arise from chromosome entanglements and breakages during
meiotic prophase; also from recombination between
transposable elements
o Cause linear rearrangement of genes in a chromosome
o In inversion heterozygotes , a loop forms from the pairing of
the inverted and non-inverted regions

37. Translocation
o When a segment of one chromosome becomes
attached to another
o In reciprocal translocations two non-homologous
chromosomes exchange genetic material
o Usually generate so-called balanced translocations
o Usually without phenotypic consequences
o Although can result in position effect

38. Reciprocal Translocation
• Involves two chromosomes
• One break in each chromosome
• The two chromosomes exchange broken segments

39. Robertsonian Translocation
• Named after W. R. B. Robertson who
first identified them in grasshoppers in
1916
• Most common structural chromosome
abnormality in humans
– Frequency = 1/1000 livebirths
• Involves two acrocentric
chromosomes
• Two types
– Homologous acrocentrics involved
– Non-Homologous acrocentrics
involved
+ =
lost
+ =
lost

40. Robertsonian Translocation
 This translocation occurs as such
 Breaks occur at the extreme ends
of the short arms of two non-
homologous acrocentric
chromosomes
 The small acentric fragments are
lost
 The larger fragments fuse at their
centromeic regions to form a single
chromosome
 This type of translocation is the most
common type of chromosomal
rearrangement in humans

41. Isochromosome & Ring Chromosome
o Mirror image chromosome
o Loss of one arm with
duplication of other
Loss of p-arm Duplication of q-arm
o Breaks occur in both arms of a
chromosome.
o The two broken ends anneal; the two
acentric fragments are lost.
o Results in double deletion (in p and in q).
o Epilepsy, mental retardation and
craniofacial abnormalities

42. Induction of Chromosomal Aberrations
by Carbamate Fungicide in Fish
Clarius batrachus (Asian Catfish)
Ajay Singh and Pallavi Srivastava
November 2013
ISSN 2276-7118

43. Abstract
Chromosomal studies have received considerable attention, in part from a growing
interest in the evaluation of genotoxicity of environmental toxicants and carcinogenns.
In view of fast growing agricultural applications of chemicals, fertilizers and pesticides,
the evaluation of their genotoxic potential is necessity to conduct adequate hazard
and to produce safer and sustainable aquatic environment. In this paper genotoxity of
fungicide, Mancozeb concluded that acute exposure of fungicide induced cytogentic
effects, as the incidence of chromosome aberrations (CA) was positively correlated
with duration of exposure. Fishes of control group was maintaned without any
treatment, positive control group was treated with mitomycin-C and two experimental groups
were exposed to sub-lethal doses of Mancozeb (11.43mg/l and 22.87 mg/l). After 24h, 48h,
72h, or 96h of exposure the mitotic index was significantly (p<0.05) decreased in kidney
tissue of fish. These findings thus indicate that Mancozeb is able to induce genotoxic
effect in catfish.

44. Thank
You!
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