1. Genetic Pedigrees

2. What is a Pedigree? A pedigree is a family tree.
This tree represents genetic information of a family over several generations.
A pedigree typically maps one specific disease or trait.

3. What does a Pedigree look like?

4. How do we construct a Pedigree?
Basic Symbols
Connecting Symbols
Female
Male
Affected
Carrier
Autosomal
X-linked
Deceased
Married
Children

5. How do we organize a Pedigree?
Each person on the pedigree is numbered from left to right, starting at the top.
Each generation is indicated with a Roman numeral on the left side of the pedigree.
Siblings are placed in birth order, with the oldest on the left to the youngest on the right.

6. I 1 2 II 2 3 4 1
III 1 2 3 IV 1 2 4 3

7. How do we read a Pedigree?
First you have to determine if the pedigree is showing an autosomal disease or X-linked disease.
Autosomal means the disease is attached to any chromosomes other than X or Y.
X-linked means the disease is attached to the X chromosome.
If most of the males in the pedigree are affected, the disorder is X-linked
If it is a 50/50 ratio between men and women who are affected, the disorder is autosomal.

8. Is this Autosomal or X-linked?

9. Reading a Pedigree
The second step is to determine whether the disorder is dominant or recessive.
Dominant- One of the parents must have the disorder.
Recessive- neither parent has to have the disorder because the parents can be heterozygous.

10. Dominant or Recessive?
Recessive

11. Dominant or Recessive?
Dominant