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Pedigree Charts: Genetics Family Tree Analysis

Explore the importance of pedigree charts in genetic history. Learn how to interpret symbols, identify generations, and understand inheritance patterns of diseases. Examples provided for better comprehension.

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Pedigree Charts: Genetics Family Tree Analysis

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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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