1 Pedigrees Suppose you wanted to learn about an inherited trait present in your family. One method could be using a pedigree. A pedigree is a chart of symbols showing the relationships within a family & a specific trait that each member may exhibit.

2 Pedigree Symbols

3 Connecting Pedigree Symbols Married Couple Siblings Examples of connected symbols:

4 What does a pedigree chart look like?

5 Interpreting a Pedigree Chart Determine whether the disorder is dominant or recessive. – If the disorder is dominant, one of the parents must have the disorder. – If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.

6 Example of Pedigree Charts Dominant or Recessive?

7 Example of Pedigree Charts Dominant or Recessive?

Mr. and Mrs. Smith had 3 children – Susie, Sandra, & Steven. When the children were still young, Mr. Smith was killed in an automobile accident. Three years after the accident, Mrs. Smith married Mr. Jones. Mr. Jones had 1 daughter, Joy. Mr. Jones & Joy ’ s mother had been divorced when Joy was 6. Draw a pedigree for each of the following families: 1. The Smith family before the automobile accident. 2. The Smith-Jones family after the new marriage.

9 Interpreting a Pedigree Chart Determine if the pedigree chart shows an autosomal or X-linked disease. – 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 the disorder is autosomal.

10 Example of Pedigree Charts Is it Autosomal or X-linked?

11 Summary Pedigrees are family trees that explain your genetic history. Pedigrees are used to find out the probability of a child having a disorder in a particular family. To begin to interpret a pedigree, determine if the disease or condition is autosomal or X-linked and dominant or recessive.

12 Female Carriers

13 Mr. and Mrs. Smith had 3 children – Susie, Sandra, & Steven. When the children were still young, Mr. Smith was killed in an automobile accident. Three years after the accident, Mrs. Smith married Mr. Jones. Mr. Jones had 1 daughter, Joy. Mr. Jones & Joy ’ s mother had been divorced when Joy was 6. Draw a pedigree for each of the following families: 1. The Smith family before the automobile accident. 2. The Smith-Jones family after the new marriage. Imagine you are a genetic counselor. The pedigree shown illustrates albinism. A couple from the family have come to you for advise about how the trait is inherited. Your task is to determine whether the allele for albinism is dominant or recessive. Some doctors include pedigrees in patients ’ medical charts. List at least 3 types of things that a doctor might include in a pedigree that most people would probably not include in a family tree. Choose an inherited trait & create a pedigree word problem that will be drawn by a fellow biology student. Include 4 generations.