1. Inheritance - Pedigrees
A pedigree is a graphical representation of the generations of a family
Can be used to trace genetic disorders or a person who is a carrier for a disorder
Tool used by genetic counselors and doctors

2. Inheritance - Pedigree
Set-up:
Males represented by squares
Females represented by circles
Darkened circle/square represents a person with the disorder
Half darkened represents a carrier for a disorder
Blank/white represents a person without the disorder
Mating is shown with a horizontal line connecting a circle and square
Offspring are shown with vertical lines connecting to the parents

3. Inheritance - Pedigree
Modes of Inheritance:
Autosomal Dominant: affected individual has an affected parent; cannot skip generations.
Autosomal Recessive: affected individual may not have an affected parent; can skip generations.
Both parents could be heterozygous
X-link Recessive: affected individual may not have an affected parent.
Males are more likely to be affected than females.
Females may not have the disease but can pass it on (carrier)
Affected males must have an affected or carrier mother

4. Inheritance - Pedigree
Examples: 1. 2.
Which mode of inheritance does this pedigree likely show?
Autosomal dominant
What are the genotypes of individuals 1 – 5? Use letter “a”.
1 = aa
2 = Aa
3 = aa
4 = Aa
5 = aa
Which mode of inheritance does this pedigree likely show?
What is the likely genotype for individual 4?
c) What is the likely genotype for individual 5?