1. Example of Trait = Albinism
Pedigree Charts
Show relationships within a family
In genetics: Used to show how an inherited trait is passed through a family
Example of Trait = Albinism

2. Symbols Circle = female Square = male
Normal or without trait = unshaded
Trait = shaded

3. Symbols
If an individual has one recessive allele for a trait, the person is a carrier. This is shown with a half-shaded square or circle.

4. Symbols
Married couple or couple producing offspring = horizontal line connecting midpoint of circle and square

5. Symbols One offspring Multiple Offspring
How do you differentiate between a brother and sister and a husband and wife on a pedigree?
Multiple Offspring

6. Generations Each generation is (often) labeled with a Roman numeral.
Oldest generation at top of pedigree
Current generation at bottom

7. Generations Individuals in each generation may be numbered or named.
Individuals in each generation may be numbered or named.
Siblings are placed in birth order from left to right.

8. Analysis How many offspring were produced by generation 1?
Number of boys? Girls?
How many of generation II were married with children?
Deaths are shown with a slash.

9. Traits Autosomal recessive traits Autosomal dominant traits
Sex-linked traits
Autosomal- all other chromosomes
Sex-linked- X or Y chromosome

10. Autosomal Recessive
Appears only in individuals who receive TWO copies of the affected allele (one from each parent)
Male and females (roughly) equally affected
Does not appear in every generation

11. Autosomal Recessive

12. Analysis of a Recessive Trait
How many individuals on this pedigree have the trait?
How many are carriers?

13. Sickle Cell Anemia

14. Sickle Cell Anemia Red blood cell disorder Changes shape of blood cell
Not flexible and can stick to vessel walls
Causes blockage that slows or stops the flow of blood
Oxygen cannot reach nearby tissues

16. Autosomal Dominant
An alteration in ONE copy of the affected gene (allele) is enough to lead to disease
Male and females (roughly) equally affected
Does not skip a generation

17. Autosomal Dominant

18. Dominant or Recessive Trait?

19. Dominant or Recessive Trait?

20. Sex-linked traits If a gene is found on the X chromosome
Males exhibit more often than females
Females: XX (would need to inherit from the mother AND father)
Males: XY (only need to inherit from the mother)
Example: red-green colorblindness

21. Disorders Autosomal recessive cystic fibrosis Albinism
Beta- thalassaemia
Sickle cell
Autosomal dominant
Dwarfism
Huntingtons
Marfan syndrome
Neurofibromitosis
Tuberous Schlerosis
Sex linked
Hemophilia
Duchennes muscular dystrophy
Beckers muscular dystrophy
Red-green colorblindness