Genetic Disorders : Autosomal & Sex Linked Traits

1. Genetic Disorders:Autosomal &Sex Linked Traits

2. Karyotype: All of the chromosomes that an individual has in their body • Autosomes: All chromosomes except your sex chromosomes • Sex Chromosomes: Determine which gender you will be

4. Autosomal Recessive Disorders • Recessive genes found on an autosome that cause a particular disorder. • DD = Normal • Dd = Carrier • dd = Affected by disorder

5. 2 Examples of Autosomal Recessive Disorders

6. Tay-Sachs Disease • A genetically caused disease in which thegene to make the enzyme Hex-A (Hexosaminidase A) is not working. • Hex-A is an enzyme that breaks down thelipid GM2 ganglioside. • Without Hex-A this lipidaccumulates on nerve cells, specifically in the brain causing severe brain damage. • Victims of this disorder do not livepast age 5

7. Tay-Sachs Brain

8. Tay-Sachs Carriers Offspring: 25% Normal 50% Carriers 25% Tay-Sachs

9. Common in Eastern European Ashkenazi Jews • This is a group of people descendent of medieval Jews from the Rhineland area. (Rhineland: near the river Rhine in Germany)

10. Cystic Fibrosis 7q31 • Thick mucus is produced by the body • Mucus fills lungs causing lung infections • Mucus blocks pancreas which causes digestive problems • Mucus can block bile ducts in liver causing liver failure.

11. Cystic Fibrosis

12. Cystic Fibrosis Effects 1/30 Caucasians

13. Carriers of Cystic Fibrosis Offspring: 25% Normal 50% Carriers 25% Cystic Fibrosis

15. Autosomal Dominant Disorders • Dominant genes found on an autosome that cause a particular disorder. • Affects people after their reproductive years • DD = Affected • Dd = Affected • dd = Normal

16. 1 Example

17. Huntington’s Disease • Genetically programmed degeneration of brain cells. • Mood swings, loss of muscle control, loss of memory and inability to learn, death. • hh = Normal • HH or Hh = will get and die of this disease

18. Person with Huntington’s and a person without Huntington’s Hh x hh Offspring: 50% Huntington’s 50% Normal

19. Huntington’s is most common in Venezuela

20. Trisomy: An autosomal disorder: person has 3 homologous chromosomes instead of 2 homologous chromosomes-Often die between conception (when sperm meets egg) and 1 year old.

21. 1 Example

22. Down Syndrome: • Genotype: 3 copies of 21st chromosome

23. Chances of Getting Downs • Age 25: 0.076% • Age 35: 0.27% • Age 45: 3.3%

24. Phenotype: Skin folds above the eye, some cardiac deformities, some levels of mental retardation, extra large tongue

25. Phenotype: Skin folds above the eye, some cardiac deformities, some levels of mental retardation, extra large tongue

26. Downs Karyotype

27. Sex Linked Traits

28. Sex Linked Traits • Traits that occur on the X or Y chromosome

29. 2) X Linked: A trait that occurs on the X chromosome. a) More likely to affect men because men only get one X chromosome. b) Women must get two recessive chromosomes to show the disorder

30. 3) Colorblind Phenotype: • The affected person does not have color vision: usually no green or red (men: 8%, women 0.4%)

31. How to write a Alleles for Sex Linked Traits • Women: • Normal: XBXB • Carrier: XBXb • Colorblind: XbXb • Men: • Normal: XBY • Colorblind: XbY

32. Colorblind Test! • You will be given a colorblind test. • You will see circles with many colors of dots • The dot pattern makes up a number • What number do you see?

33. With Color Vision:

34. Color Blind Test What number do you see?

35. Color Blind Test What number do you see?

36. This what you would see if you were color blind What number do you see?

37. Color Blind Test What number do you see?

38. Color Blind Test What number do you see?

39. Color Blind Test What number do you see?

40. Color Blind Test What number do you see?

41. With color vision you see this: But if you were red-green colorblind…. You would see the #: 5

42. What do the colorblind see? Types of Colorblindness

43. Types of Colorblindness – Normal No color vision Protanopia: no red Deuteranopia: no green Tritanopia: no blue http://www.visitliverpool.jp/nature/images/knowsley-wildflower.jpg

44. Hemophilia • A genetic sex linked gene that affects the way your blood clots. (affects clotting factor VIII and IX) • Small cuts, scrapes and bruises can be life threatening • 1 in 10, 000 males • 1 in 100,000,000 females

45. Common amongst royalty in Europe

46. Queen Victoria = Carrier

47. 9 i. How many kids did Victoria have? ________ ii. How many kids were carriers?________ # of kids effected? __________ iii. Were any girls affected by the disorder?______ Boys? _____ How many?_____ 2 1 no yes 10

49. Tay-Sachs Pedigree ? ?

50. Turner Syndrome • Genotype: XO • Phenotype: • Female • Some women are normal • Many are infertile • do not grow/develop normally, are short statured.