4 chromosomal aberrations ks

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4 chromosomal aberrations ks

  1. 1. Chromosomal Aberrations DR.KIRTI SOLANKE 1
  2. 2. Types of Chromosomes 2
  3. 3. Types of chromosomal aberrations/ abnormalitiesNUMERICAL STRUCTURAL• ANEUPLOIDY • Translocations• POLYPLOIDY • Deletions • Insertions • Inversions • Rings, Isochromosomes • Different cell lines (mixoploidy) • Mosaicism • Chimerism
  4. 4. Discuss mechanism of anomaly
  5. 5. Discuss mechanism of anomaly
  6. 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
  7. 7. Trisomy 21; Down Syndrome Causes-trisomy,translocation,mosaicism• 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
  8. 8. Brushfield spots onirisHypotonia ofmuscles
  9. 9. Simian Crease
  10. 10. TURNER’S SYNDROME 45XO • Causes: – Non-dysjunjtion – Mosaicism – Ring Chromosome – Deletion – Isochromosome • Short stature • Widely spaced nipples • Carrying angle at elbow
  11. 11. Klinefelters Syndrome (47, XXY)
  12. 12. STRUCTURAL ABERRATIONS 20
  13. 13. Structural Abnormalities Of Chromosomes• Result from the breaks in the chromosomes• Causative factors for the breaks: • Radiation, Drugs ,Viruses.• Types of structural abnormalities are: 1. Deletion 2. Insertion 3. Duplication 4. Inversion 5. Isochromosome 6. Translocation 7. Transposition 8. Ring Chromosome 21
  14. 14. Structural Abnormalities Of Chromosomes• Classified as – Stable & Unstable• Also classified as – Balanced & Unbalanced 22
  15. 15. Terminal Deletion 23
  16. 16. Interstitial Deletion 24
  17. 17. Interstitial Deletion 25
  18. 18. Deletions• May arise through unequal crossing over A B C D E F G x A B C D E F G A B C D E G A B C D E F F G Deletion Duplication
  19. 19. INSERTION 27
  20. 20. Insertion 28
  21. 21. Insertion& Duplication 29
  22. 22. INVERSION 30
  23. 23. Inversions• Produced through breakage and reassociation of chromosome D E C A B F G
  24. 24. Inversions• Produced through breakage and reassociation of chromosome D E C A B F G
  25. 25. INVERSIONPericentric Inversion 33
  26. 26. Inversion: Pericentric & Paracentric Pericentric 34
  27. 27. Paracentric 35
  28. 28. Pericentric Paracentric Inversion InversionINVERSION 36
  29. 29. Isochromosome(Transverse centromeric division) 37
  30. 30. Isochromosome (Transverse centromeric division)Example:•Long arm of X- chromosome remains, short arms lost•Cytogenetic variant of Turner’s syndrome 38
  31. 31. Isochromosome 39
  32. 32. TRANSLOCATIONS 40
  33. 33. 41
  34. 34. Reciprocal Translocation video
  35. 35. Robertsonian Translocation 45
  36. 36. Acrocentric Chromosomes (Group D & G) 47
  37. 37. Reciprocal (Balanced) Robertsonian Translocation:translocation: Between two acrocentric chromosomeBetween any two chromosomes e.g. Chromosome 13 & 21Translocation 48
  38. 38. Robertsonian TranslocationCommon Robertsonian translocations are confined to theacrocentric chromosomes 13, 14, 15, 21 and 22; short arms of thesechromosomes contain no essential genetic material. 49
  39. 39. 50
  40. 40. Ring Chromosome 51
  41. 41. Ring Chromosomee.g. r(22): Ring Chromosome no.22 52
  42. 42. STRUCTARAL ABERRATION

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