1. Diseases and karyotypes
Definitions
Autosomes- any chromosome that is not a sex chromosome. Not the “X” or “Y”
Sex-linked- genes located on the sex chromosome. Usually on the “X”
Nondisjunction- A chromosome mishap in meiosis

2. Abnormal numbers of autosomes
Metaphase chromosomes are photographed;
the chromosome pictures are then enlarged and
arranged in pairs by a computer according to length and location of the centromere.

3. Abnormal numbers of autosomes
This chart of chromosome pairs is called a karyotype, and it is valuable in identifying unusual chromosome numbers in cells.

4. A Karyotype is a photograph of the chromosomes of a single cell.

6. Another view

7. Normal
Female

8. Normal
Male

9. ?

12. Colchicine added to cells Microscope zooms in Cells broken open
Picture of chromosomes taken
Chromosomes cut up and arranged

14. Chromosomal Disorders
Individuals are missing a chromosome or have an extra chromosome

15. Down syndrome: Trisomy 21
Down syndrome is the only autosomal trisomy in which affected individuals survive to adulthood.
It occurs in about one in 700 live births.

16. Down syndrome: Trisomy 21
Down syndrome is a group of symptoms that results from trisomy of chromosome 21.
Individuals who have Down syndrome have at least some degree of mental retardation.
The incidence of Down syndrome births is higher in older mothers, especially those over 40.

17. Chromosome 21
Down's Syndrome

19. Abnormal numbers of sex chromosomes
Many abnormalities in the number of sex chromosomes are known to exist.
An X chromosome may be missing (designated as XO) or there may be an extra one (XXX or XXY). There may also be an extra Y chromosome (XYY).

20. Klinefelter’s
Syndrome

21. XXY Klinefelter's Poor beard growth Tend to grow fewer chest hairs
Breast development
Wide hips
Long legs
Narrow shoulders
Klinefelter's

22. Karyotype of a male with Klinefelter’s syndrome

23. Short (<59”)
Webbed neck
Sterile
Low hairline XO
Turner's Syndrome

24. Karyotype of a female with Turner’s syndrome

25. Autosomal Genetic Disorders
These are a result of genes on the 22 pairs of chromosomes that are not the sex chromosomes (not X and Y)

26. Sickle Cell Anemia Autosomal Recessive Affects the blood
Symptoms: impaired blood circulation, organ damage
Defect: Abnormal hemoglobin molecules – RBC’s
1/500 African Americans -If heterozygous will not get malaria

27. Section 12.3 Summary – pages 323 - 329
Sickle-cell disease
Abnormally shaped blood cells, slow blood flow, block small vessels, and result in tissue damage and pain.
Normal red blood cell
Sickle cell
Section 12.3 Summary – pages

28. cystic fibrosis

29. Cystic Fibrosis
Recessive allele
Affects the lungs and digestive tract
Characterized by thick mucus in lungs and digestive tract
Food is not digested properly
Breathing is difficult - frequent lung infections

30. .Most common lethal genetic disorder in white Americans.
Approximately one in 28 white Americans carries the recessive allele, and one in 2500 children born to white Americans inherits the disorder.

31. This is a frame shift mutation
Cystic Fibrosis
On chromosome 7 there is a mutation in a gene that causes a thick mucus to develop
This is a frame shift mutation

33. Huntington's Disease

34. Huntington's Disease Autosomal dominant—carriers GET the disease
Affects the central nervous system
Causes nerve death in the brain. Starts with spasms and eventually leads to a vegetable like state and death. Onset between 30 and 50.

35. Defect on Chromosomes number 4
Huntington’s Disease
Huntington disease affects an estimated 3 to 7 per 100,000 people of European ancestry. The disorder appears to be less common in some other populations, including people of Japanese, Chinese, and African descent.
Defect on Chromosomes number 4

36. Section 12.1 Summary – pages 309 - 314
Typical Pedigree of Huntington’s Disease I 1 2 II 1 2 3 4 5
III 1 2 3 4 5
Section 12.1 Summary – pages

38. PKU

39. Phenylketonuria (PKU)
Autosomal recessive
Affects: brain
Symptoms: Failure of brain to develop in infancy; if untreated causes death.
Defect: Caused by absence of enzyme that converts phenylalanine to tyrosine (amino acids)
1/18,000 urine test, treated by diet until puberty.

40. Phenylketonuria (PKU)
Most common in people of Norwegian and Swedish descent.

41. Symptoms of PKU New born appears normal.
Once baby starts drinking milk, which is high in phenylalanine, damage occurs

42. Symptoms
Build up in phenylalanine causes severe central nervous system damage resulting in mental retardation.

43. Treatment of PKU All newborns are tested for PKU.
Changes in diet can prevent damage. Given a diet low in phenylalanine until the brain is fully developed.

44. Section 12.1 Summary – pages 309 - 314
Phenylketonuria
Phenylketonurics: Contains Phenylalanine
Section 12.1 Summary – pages

45. Section 12.1 Summary – pages 309 - 314
Tay-Sachs disease
Tay-Sachs (tay saks) disease is a recessive disorder of the central nervous system.
In this disorder, a recessive allele results in the absence of an enzyme that normally breaks down a lipid produced and stored in tissues of the central nervous system.
Because this lipid fails to break down properly, it accumulates in the cells.
Section 12.1 Summary – pages

46. Symptoms of Tay-Sachs Disease
Blindness
Progressive loss of movement
Mental deterioration
Death by age 5.

47. Section 12.1 Summary – pages 309 - 314
Typical Pedigree for II 1 2 3 4
Tay-Sachs
III 1 2 3 IV 1
Section 12.1 Summary – pages

48. Sex-linked traits
These are genes that are found on the X chromosome. They are generally more common in males than in females.
Females need to have it on both their X chromosomes ( get from mom and dad)
Since males only have 1 X chromosome, they only need to have received the allele from their mother for the trait to show.

49. Hemophilia
Sex-linked trait

50. Hemophilia X-linked recessive
Defect: defective form of blood-clotting agent.
Symptoms: failure of blood to clot
About one male in every has hemophilia, but only about one in 100 million females inherits the same disorder.

51. Section 12.3 Summary – pages 323 - 329
Hemophilia: An X-linked disorder
Males inherit the allele for hemophilia on the X chromosome from their carrier mothers. One recessive allele for hemophilia will cause the disorder in males.
Females would need two recessive alleles to inherit hemophilia.
Section 12.3 Summary – pages

56. Some genetic disorders are both genetic and environmental
Some genetic disorders are both genetic and environmental. People inherit the tendency to a trait, but how and when it is expressed depends on environmental factors such as diet, exercise, exposure to chemicals, etc.

57. Diabetes
Asthma
Cardiovascular
Disease