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Genetic Disorders: Autosomal & Sex Linked Traits

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Presentation on theme: "Genetic Disorders: Autosomal & Sex Linked Traits"— Presentation transcript:

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 the gene to make the enzyme Hex-A (Hexosaminidase A) is not working. Hex-A is an enzyme that breaks down the lipid GM2 ganglioside. Without Hex-A this lipid accumulates on nerve cells, specifically in the brain causing severe brain damage. Victims of this disorder do not live past 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 5 With color vision you see this:
But if you were red-green colorblind…. You would see the #: 5

42 What do the colorblind see?

43 Types of Colorblindness –
Normal No color vision Protanopia: no red Deuteranopia: no green Tritanopia: no blue

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 2 1 no yes 10 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.

51 Klinefelter’s Syndrome
Genotype: XXY Phenotype: Male Diminished activity of testes Reduced fertility

52 Triplo-X Genotype: XXX Phenotype: Normal

53 Hermaphrodites ?!? Hermaphrodite: An individual that has all female reproductive parts, and all male reproductive parts No such thing in Humans

54 Hermaphrodites ?!? However: XY females are as close as you can get
Genotype: XY Phenotype: Look like women Do not have uterus, don’t have periods Some have testes instead of ovaries

55 Models have a high % of XY women.

56 XY women show some “male-like” features that make them good models
Taller than most women Chiseled Jaw Good Muscle definition Don’t have as much body fat

57 Turner syndrome one X Klinefelter syndrome XXY Triplo-X (normal)


59 What is Turner syndrome?
Turner syndrome describes females who have a common constellation of problems because they are missing all or part of an X chromosome. Some will have few, if any, noticeable problems, while others may have many. Some of these problems include: short stature lymphedema (a collection of lymph fluid in the tissues; often causing puffiness of the hands and feet in newborns) gonadal failure (resulting in delayed or absent sexual development, infertility) frequent ear infections progressive nerve hearing loss strabismus (wandering or crossed eye) unusual physical features such as a narrow palate, receding jaw, webbed neck, low hairline, prominent ears, broad chest, and narrow fingernails and toenails that point upwards structural abnormalities of the heart and/or the aorta (the main vessel carrying blood away from the heart) structural abnormalities of the kidneys hypothyroidism multiple moles non-verbal learning disability


61 Patiño is considered by science as an “androgen insensitive
Patiño is considered by science as an “androgen insensitive.” A fetus of this class develops testes on the eighth week, but the “androgen receptors” are faulty and thus fail to detect the presence of male hormones, even if these are present in the body. In the end, the child is delivered as a girl. Her breasts may enlarge at puberty but she will never menstruate, as her uterus has not developed. Approximately one of every 20,000 persons is an androgen insensitive. And about one of every 2,500 females has a single X chromosome. The XY woman, as I shall distinguish her, is actually no different from the XX woman—well, other than she will not physically bear children. There are even a significant number of Western XY women who are into the modeling profession. In this new millennium, we must encourage a deeper learning about what determines our gender. A healthy discussion and research on this will aid us in the compassionate understanding of our diversities. Myths that surround gender expression must be set straight all together in the light of scientific explanations. Only by welcoming such evolution in popular beliefs will we be liberated from social condescension.

62 Turner’s Syndrome Karyotype

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