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Pedigree Charts

Pedigree Charts. What is a Pedigree?. Pedigree chart of the genetic history of a family over several generations. Since you cannot make humans of different types breed together a pedigree chart offers an ethical way of studying human genetics. Studying human genetics.

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Pedigree Charts

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  1. Pedigree Charts

  2. What is a Pedigree? • Pedigree • chart of the genetic history of a family over several generations. • Since you cannot make humans of different types breed together a pedigree chart offers an ethical way of studying human genetics.

  3. Studying human genetics • Today genetic engineering has new tools to offer doctors studying genetic diseases • A genetic counselor will still use pedigree charts to help determine the distribution of a disease in an affected family

  4. Male Female Constructing a Pedigree

  5. A marriage with five children, two daughters and three sons. The middle son is affected by the condition. Eldest child  Youngest child Symbols used in pedigree charts • Normal male • Affected male • Normal female • Affected female • Marriage (mating)

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

  7. Affected Deceased Symbols in a Pedigree Chart

  8. I II III IV Organizing the pedigree chart • Generations are identified by Roman numerals

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

  10. Interpreting a Pedigree Chart • Determine if the pedigree chart shows an autosomal or (sex) X-linked disease. • If most of the males in the pedigree are affected by the disorder, then it is (sex) X-linked • If it is a 50/50 ratio between men and women the disorder is autosomal.

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

  12. Answer • Autosomal

  13. 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.

  14. Example of Pedigree Charts • Dominant or Recessive?

  15. Answer • Dominant

  16. Example of Pedigree Charts • Dominant or Recessive?

  17. Answer • Recessive

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