8 Chromosome Disorder

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8 Chromosome Disorder

  1. 1. Chromosome disorders Weiying Jiang Department of Medical Genetics P33
  2. 3. Human chromosome
  3. 4. What is chromosome? Chromosomes are complex structures located in the cell nucleus, they are composed of DNA, histone and non-histone proteins, RNA , and polysaccharides. They are basically the "packages" that contain the DNA.
  4. 6. A group——1 ~ 3 B group——4 ~ 5 C group——6 ~ 12 +X D group——13 ~ 15 E group——16 ~ 18 F group——19 ~ 20 G group——21 ~ 22 +Y Classification
  5. 7. Metacentric (Chromosome 1) Submetacentric (Chromosome 9) Acrocentric (Chromosome 14)
  6. 8. Methods of chromosome analysis Karyotype analysis
  7. 9. Methods of chromosome analysis Karyotype analysis (G banding )
  8. 10. Methods of chromosome analysis Fluoresent in-situ hybridization (FISH) Utilizing fluorescently labeled DNA probes to detect or confirm gene or chromosome abnormalities that are generally beyond the resolution of routine Cytogenetics
  9. 11. Metaphase FISH
  10. 12. Interphase FISH FISH can be used in interphase cells to determine the chromosome number of one or more chromosomes as well as to detect some specific chromosome rearrangements that are characteristic for certain cancers. The primary advantage of interphase FISH is that it can be performed very rapidly if necessary, usually within 24 hours, because cell growth is not required.
  11. 14. Comparative Genomic Hybridization ( CGH ) ATCGGATCATGCGTA TAGCCTAGTACGCAT
  12. 17. Disadvantages : Resolution Technical difficulties 10 mega-bases for losses 2 mega-bases for gains Providing the start point for position cloning, but the precise localization
  13. 18. Array CGH
  14. 21. Advantages : Resolution 30,000 overlapping mapped clones (one clone per mega-base) Oligonucleotide array includes up 500,000 probes
  15. 22. Chromosome abnormality Numerical abnormality Structural abnormality Aneuploidy Polyploidy translocation deletion insertion inversion rings isochromosome
  16. 23. Numerical abnormality 46 chromosomes 23 chromosomes = one set of chromosomes
  17. 24. Diploidy
  18. 25. Aneuploidy: One or a few chromosomes ,except 23 ones , above or below the normal chromosome number. For example, three number 21 chromosomes or trisomy 21.
  19. 26. The common aneuploidy: Patau syndrome: (trisomy 13) Edwards syndrome: (trisomy 18) Down’s syndrome: (trisomy 21)
  20. 27. The common aneuploidy: Turner’s syndrome: (45, X)
  21. 28. Normal XX X X l l l l
  22. 29. Non-disjunction In meiosis
  23. 30. Non-disjunction During Mitosis Mosaicism
  24. 31. Polyploidy More than two sets of chromosomes per nucleus. 23 chromosomes = one set of chromosomes 69,XXY 92,XXXY
  25. 32. Diandry Digyny
  26. 33. Structure of chromosome abnormality
  27. 34. 46,XY,t(5;8)(q31.1;p23).
  28. 35. A C B D Synapsis
  29. 37. Robertsonian Translocation
  30. 39. 46,XX,del(16)(q13q22
  31. 40. 46,XY,inv(10)(q11.23q26.3) . Inversion
  32. 41. A C B D Synapsis
  33. 42. Pericentric inversion Paracentric inversion 1 2 3 4 1 4 2 3 1 2 4 3
  34. 43. 46,XY,+13,dic(13;14)(p11.2;p11.2) .
  35. 44. Ring chromosome
  36. 45. Chromosome abnormality Numerical abnormality Structural abnormality Aneuploidy Polyploidy translocation deletion insertion inversion rings isochromosome
  37. 46. Thank you !

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