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Pedigree charts

  1. 1. Overview <ul><li>What is a pedigree? </li></ul><ul><ul><li>Definition </li></ul></ul><ul><ul><li>Uses </li></ul></ul><ul><li>Constructing a pedigree </li></ul><ul><ul><li>Symbols </li></ul></ul><ul><ul><li>Connecting the symbols </li></ul></ul><ul><li>Interpreting a pedigree </li></ul>
  2. 2. What is a Pedigree? <ul><li>A pedigree is a chart of the genetic history of family over several generations. </li></ul><ul><li>Scientists or a genetic counselor would find out about your family history and make this chart to analyze. </li></ul>
  3. 3. Constructing a Pedigree <ul><li>Male </li></ul><ul><li>Female </li></ul>
  4. 4. Connecting Pedigree Symbols <ul><li>Married Couple </li></ul><ul><li>Children </li></ul>Examples of connected symbols:
  5. 5. Example <ul><li>What does a pedigree chart look like? </li></ul>
  6. 6. Symbols in a Pedigree Chart
  7. 7. Interpreting a Pedigree Chart <ul><li>Determine if the pedigree chart shows an autosomal or sex-linked disease. </li></ul><ul><ul><li>If most of the males in the pedigree are affected the disorder is sex-linked </li></ul></ul><ul><ul><li>If it is a 50/50 ratio between men and women the disorder is autosomal. </li></ul></ul>
  8. 8. Example of Pedigree Charts <ul><li>Is it Autosomal or sex-linked? </li></ul>
  9. 9. Answer <ul><li>Autosomal </li></ul>
  10. 10. Interpreting a Pedigree Chart <ul><li>Determine whether the Trait (disorder) is dominant or recessive. </li></ul><ul><ul><li>If the disorder is dominant, one of the parents must have the disorder. </li></ul></ul><ul><ul><li>If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous. </li></ul></ul>
  11. 11. Example of Pedigree Charts <ul><li>Dominant or Recessive? </li></ul>
  12. 12. Answer <ul><li>Dominant </li></ul>
  13. 13. Example of Pedigree Charts <ul><li>Dominant or Recessive? </li></ul>
  14. 14. Answer <ul><li>Recessive </li></ul>
  15. 15. Summary <ul><li>Autosomal Dominant - condition is transmitted in unbroken descent from each generation to the next </li></ul><ul><ul><li>BB or Bb – affected’ </li></ul></ul><ul><li>Autosomal Recessive – trait will only show when homozygous (bb) </li></ul><ul><ul><li>Will skip generations </li></ul></ul>
  16. 16. Summary <ul><li>Sex Linked </li></ul><ul><ul><li>Dominant </li></ul></ul><ul><ul><ul><li>Trend: does not skip generations </li></ul></ul></ul><ul><ul><ul><li>Female: BB or Bb / Male: B </li></ul></ul></ul><ul><ul><ul><li>Any males must have mothers with trait </li></ul></ul></ul><ul><ul><li>Recessive </li></ul></ul><ul><ul><ul><li>Trend: skips generations </li></ul></ul></ul><ul><ul><ul><li>Female: bb / Male: b </li></ul></ul></ul><ul><ul><ul><li>Most affected individuals will be male </li></ul></ul></ul><ul><ul><ul><li>Females with trait must have father with trait </li></ul></ul></ul>