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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 this chart to analyze.

  4. Male Female Constructing a Pedigree

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

  6. CHILDREN FROM A MARRIED COUPLE HOW MANY MALE OFFSPRING ARE THERE? FEMALE? Children are siblings

  7. Other Symbols Affected X-LINKED CARRIER

  8. AUTOSOMAL CARRIER DECEASED

  9. Example • What does a pedigree chart look like?

  10. Pedigree Vocabulary • Autosomal gene- a gene found on any chromosome except for the sex chromosome. These are chromosomes numbered 1-22 • X-linked gene- a gene found on a chromosome designated as a sex chromosome (X or Y).

  11. 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.

  12. Example of Pedigree Charts • Is it Autosomal or X-linked?

  13. Answer • Autosomal

  14. 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.

  15. Determining if a Pedigree Dominant or Recessive • Dominant pedigree • 1) Every affected individual has at least one affected parent • 2) Affected individuals who mate with unaffected individuals have a 50% chance of transmitting the trait to each child • 3) Two affected individuals may have unaffected children (heterozygous)

  16. Determining if a Pedigree Dominant or Recessive • Recessive pedigrees are: • 1) An individual who is affected may have parents who are not affected • 2) All the children of two affected individuals are affected

  17. Example of Pedigree Charts • Dominant or Recessive?

  18. Answer • Dominant

  19. Example of Pedigree Charts • Dominant or Recessive?

  20. Answer • Recessive

  21. 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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