Chromosome disorders can involve numerical abnormalities like aneuploidy (having an extra or missing chromosome) or structural abnormalities such as translocations, deletions, inversions, or ring chromosomes. Karyotype analysis using G-banding and fluorescent in situ hybridization (FISH) are common methods to analyze chromosomes. Comparative genomic hybridization (CGH) and array CGH provide higher resolution to detect gains and losses of genetic material. Common aneuploidies include trisomy 21 (Down syndrome), trisomy 13 (Patau syndrome), and trisomy 18 (Edwards syndrome). Structural abnormalities involve rearrangements of chromosomal segments.

1. Chromosome disorders Weiying Jiang Department of Medical Genetics P33

3. Human chromosome

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.

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

7. Metacentric (Chromosome 1) Submetacentric (Chromosome 9) Acrocentric (Chromosome 14)

8. Methods of chromosome analysis Karyotype analysis

9. Methods of chromosome analysis Karyotype analysis (G banding )

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

11. Metaphase FISH

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.

14. Comparative Genomic Hybridization （ CGH ） ATCGGATCATGCGTA TAGCCTAGTACGCAT

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

18. Array CGH

21. Advantages ： Resolution 30,000 overlapping mapped clones (one clone per mega-base) Oligonucleotide array includes up 500,000 probes

22. Chromosome abnormality Numerical abnormality Structural abnormality Aneuploidy Polyploidy translocation deletion insertion inversion rings isochromosome

23. Numerical abnormality 46 chromosomes 23 chromosomes = one set of chromosomes

24. Diploidy

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.

26. The common aneuploidy: Patau syndrome: (trisomy 13) Edwards syndrome: (trisomy 18) Down’s syndrome: (trisomy 21)

27. The common aneuploidy: Turner’s syndrome: (45, X)

28. Normal XX X X l l l l

29. Non-disjunction In meiosis

30. Non-disjunction During Mitosis Mosaicism

31. Polyploidy More than two sets of chromosomes per nucleus. 23 chromosomes = one set of chromosomes 69,XXY 92,XXXY

32. Diandry Digyny

33. Structure of chromosome abnormality

34. 46,XY,t(5;8)(q31.1;p23).

35. A C B D Synapsis

37. Robertsonian Translocation

39. 46,XX,del(16)(q13q22

40. 46,XY,inv(10)(q11.23q26.3) . Inversion

41. A C B D Synapsis

42. Pericentric inversion Paracentric inversion 1 2 3 4 1 4 2 3 1 2 4 3

43. 46,XY,+13,dic(13;14)(p11.2;p11.2) .

44. Ring chromosome

45. Chromosome abnormality Numerical abnormality Structural abnormality Aneuploidy Polyploidy translocation deletion insertion inversion rings isochromosome

46. Thank you !