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Pedigree Charts

Pedigree Charts. The family tree of genetics. Overview. What is a pedigree? Definition Uses Constructing a pedigree Symbols Connecting the symbols Interpreting a pedigree. What is a Pedigree?. A pedigree is a chart of the genetic history of family over several generations.

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Pedigree Charts

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  1. Pedigree Charts The family tree of genetics

  2. Overview • What is a pedigree? • Definition • Uses • Constructing a pedigree • Symbols • Connecting the symbols • Interpreting a pedigree

  3. What is a Pedigree? • A pedigree is a chart of the genetic history of family over several generations. • Scientists or a genetic counselor would find out about your family history and make a pedigree chart to analyze and provide advice.

  4. Male Female Constructing a Pedigree Each generation is shown on a different ROW Married Couples are connected and children come off BELOW them Plan out the pedigree so marriages of each sibling are not interfering with the flow of the chart

  5. Connecting Pedigree Symbols Examples of connected symbols: • Fraternal twins • Identical twins

  6. Connecting Pedigree Symbols Examples of connected symbols: • Married Couple • Siblings

  7. Example Use the pedigree to answer the following: How many generations? How many married couples? How many sisters? How many sets of brothers?

  8. Affected Autosomal carrier Deceased Additional? See the chalkboard Symbols in a Pedigree Chart

  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. Answer • Autosomal Rationale: Because there are 3 females and 3 males affected

  12. 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.

  13. Example of Pedigree Charts • Dominant or Recessive? Hint: Add genotypes above each individual to determine the answer

  14. Answer • Dominant dd dd Dd Dd dd dd dd Dd Dd Dd dd dd Dd

  15. Example of Pedigree Charts • Dominant or Recessive?

  16. Answer • Recessive Dd Dd Dd Dd Dd / DD Dd / DD Dd dd dd dd Dd Dd dd

  17. 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.

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