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Pedigree Charts

Pedigree Charts. The family tree of genetics. 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. Male. Female.

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Pedigree Charts

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  1. Pedigree Charts The family tree of genetics

  2. 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.

  3. Male Female Constructing a Pedigree

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

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

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

  7. Affected Carrier (Heterozygous) Deceased Symbols in a Pedigree Chart

  8. Interpreting a Pedigree Chart • Determine if the pedigree chart shows an autosomal or Sex-linked disease. • If most of the males in the pedigree are affected the disorder is Sex-linked • If it is a 50/50 ratio between men and women the disorder is autosomal.

  9. Example of Pedigree Charts • Is it Autosomal or Sex-linked?

  10. Answer • Autosomal

  11. 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.

  12. Example of Pedigree Charts • Dominant or Recessive?

  13. Answer • Dominant

  14. Example of Pedigree Charts • Dominant or Recessive?

  15. Answer • Recessive

  16. 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 Sex-linked and dominant or recessive.

  17. Hemophilia and the Royals Hemophilia is an X-linked recessive disorder characterized by the inability to properly form blood clots. Until recently, hemophilia was untreatable, and only a few hemophiliacs survived to reproductive age because any small cut or internal hemorrhaging, after even a minor bruise, was fatal.

  18. Hemophilia and the Royals • How many generations are shown in this pedigree? • 4

  19. Hemophilia and the Royals • What is the symbol for a carrier female? • White circle • What is the symbol for a hemophilic man? • Orange square

  20. Hemophilia and the Royals • How many children did Queen Victoria have? • 9 • What ratio of her daughters were carriers? • 2/5

  21. Hemophilia and the Royals • Look at the last generation. What is the ratio of hemophilic to normal men? • 6/10 = 3/5

  22. Hemophilia and the Royals • Nicholas II of Russia • 1868-1918 • Married Princess Alexandra of Hesse, who was the granddaughter of Queen Victoria.

  23. Hemophilia and the Royals • Nicholas and Alexandra’s son, TsarevichAlexyNikolaevich • Youngest of five children and the only son • Hemophilic

  24. Hemophilia and the Royals • Gregory Rasputin (1869-1916) • Known as the “Mad Monk,” but was not really religious. • “Faith healer”

  25. Hemophilia and the Royals • In 1917, Russia had a revolution led by the communists. Nicholas was forced to abdicate (give up being Tsar) and he and his family were arrested. On July 17, Nicholas, his wife, and their five children were all killed by a Soviet firing squad.

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