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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: • Married Couple • Children

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

  6. Symbols in a Pedigree Chart

  7. Symbols used in pedigree charts • Normal male • Affected male • Normal female • Affected female • Marriage

  8. Organising the pedigree chart • A pedigree chart of a family showing 20 individuals

  9. I II III IV Organising the pedigree chart • Generations are identified by Roman numerals

  10. I II III IV Organising the pedigree chart • Individuals in each generation are identified by Arabic numerals numbered from the left • Therefore the affected individuals are II3, IV2 and IV3

  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. Example of Pedigree Charts • Dominant or Recessive?

  16. Answer • Dominant

  17. Example of Pedigree Charts • Dominant or Recessive?

  18. Answer • Recessive

  19. 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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