4 chromosomal aberrations ks

1. Chromosomal Chromosomal
AberrationsAberrations

1
DR.KIRTI SOLANKE

2. 2Types of Chromosomes

3. Types of chromosomal
aberrations/ abnormalities
NUMERICAL
•ANEUPLOIDY
•POLYPLOIDY
STRUCTURAL
•TranslocationsTranslocations
•DeletionsDeletions
•InsertionsInsertions
•InversionsInversions
•Rings, Rings,
IsochromosomesIsochromosomes
•Different cell lines Different cell lines
(mixoploidy)(mixoploidy)
•MosaicismMosaicism
•ChimerismChimerism

4. Discuss mechanism of anomaly

5. Discuss mechanism of anomaly

6. Numerical Abnormalities
•Trisomy 21: Down’s Syndrome (47,XX + 21)
•Trisomy 18: Edward’s Syndrome (47,XY + 18)
•Trisomy 13: Patau’s Syndrome (47,XY + 13)
•Trisomy of Sex Chromosome : Klinefelter
Syndrome (47, XXY)
•Trisomy X: Triple X Syndrome (47, XXX)
•Other Trisomies : Usually not viable.
•Monosomy X: Turner Syndrome (45, XO)
•Autosomal Monosomies : Not viable

10. Trisomy 21; Down Syndrome
•over 60% of conceptions aborted
spontaneously
•20% stillborn
•incidence increases sharply w/
maternal age
•1/300 for 35 year olds
•1/22 for 45 year olds
Causes-trisomy,translocation,mosaicism

13. Brushfield spots on
iris
Hypotonia of
muscles

14. Simian Crease

15. TURNER’S SYNDROME 45XO
•Causes:
–Non-dysjunjtion
–Mosaicism
–Ring Chromosome
–Deletion
–Isochromosome
•Short stature
•Widely spaced
nipples
• Carrying angle at
elbow

16. Klinefelter's Syndrome (47, XXY)

20. 20
STRUCTURAL ABERRATIONSSTRUCTURAL ABERRATIONS

21. 21
Structural Abnormalities Of Structural Abnormalities Of
ChromosomesChromosomes
•Result from the breaks in the chromosomesResult from the breaks in the chromosomes
•Causative factors for the breaks: Causative factors for the breaks:
•Radiation, Drugs ,Viruses.Radiation, Drugs ,Viruses.
•Types of structural abnormalities are:Types of structural abnormalities are:
1.1.DeletionDeletion
2.2.InsertionInsertion
3.3.DuplicationDuplication
4.4.InversionInversion
5.5.IsochromosomeIsochromosome
6.6.TranslocationTranslocation
7.7.TranspositionTransposition
8.8.Ring ChromosomeRing Chromosome

22. 22
•Classified asClassified as
–Stable & UnstableStable & Unstable
•Also classified asAlso classified as
–Balanced & UnbalancedBalanced & Unbalanced
Structural Abnormalities Of ChromosomesStructural Abnormalities Of Chromosomes

23. 23
Terminal Deletion

24. 24
Interstitial Deletion

25. 25
Interstitial Deletion

26. Deletions
•May arise through
unequal crossing over
A B C D E F G
A B C D E F G
x
A B C D E F F G A B C D E G
Deletion Duplication

27. 27
INSERTION

28. 28
Insertion

29. 29
Insertion
& Duplication

30. 30
INVERSION

31. Inversions
• Produced through breakage and
reassociation of chromosome
A
B
C
D
E
F
G

32. Inversions
• Produced through breakage and
reassociation of chromosome
A
B
C
D
E
F
G

33. 33
Pericentric Inversion
INVERSION

34. 34
Inversion: Pericentric & ParacentricInversion: Pericentric & Paracentric
Pericentric

35. 35Paracentric

36. 36INVERSION
Pericentric
Inversion
Paracentric
Inversion

37. 37
Isochromosome
(Transverse centromeric
division)

38. 38
Isochromosome Isochromosome
(Transverse centromeric division) (Transverse centromeric division)
Example:
•Long arm of X- chromosome remains, short arms lost
•Cytogenetic variant of Turner’s syndrome

39. 39Isochromosome

40. 40TRANSLOCATIONS

41. 41

44. Reciprocal Translocation video

45. 45
Robertsonian Translocation

47. 47
Acrocentric Chromosomes
(Group D & G)

48. 48
Robertsonian Translocation:
Between two acrocentric chromosome
e.g. Chromosome 13 & 21
Reciprocal (Balanced)
translocation:
Between any two chromosomes
Translocation

49. 49
Robertsonian Translocation
Common Robertsonian translocations are confined to the
acrocentric chromosomes 13, 14, 15, 21 and 22; short arms of these
chromosomes contain no essential genetic material.

50. 50

51. 51
Ring Chromosome

52. 52
Ring ChromosomeRing Chromosome

e.g. r(22): Ring Chromosome no.22

55. STRUCTARAL ABERRATION