multifactoral inheritance.txt

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multifactoral inheritance.txt
2010-12-13 18:50:49
multifactoral inheritance

multifactoral inheritance
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  1. What is a multifactoral trait?
    • Trait caused by both genetics and environment.
    • ***not sex-linked, not mendelian
  2. What type of graph is representative of Additive polygenic model?
    • Bell-Curve (25%, 50%. 25%), Majority is average
    • The 50% will contain one or two dominant (Aa, AaBb, AAbb, aaBB, AaBb)
  3. What happens to the threshhold when utilizing one type of population?
    Remains unchanged
  4. What is the main difference b/t Threshhold and Additive?
    • Threshhold: qualitative, all-or-nothing, liability curve
    • Additive: quantitative, average, bell curve
  5. Why do individuals exceed threshhold of liability?
    • 1) many genetic factors
    • 2) environmental factors
  6. If a population or sex has a higher threshhold of liability, will the occurrence rate be high or low?
  7. What are two factors used to predict recurrence risk?
    • 1) Less recurrence risk when degree of relatedness is less
    • 2) A more severe condition in a proband of a family equals a higher recurrence
  8. Rules of recurrence risk calculations
    • 1) Increases when more family members are affected
    • 2) Increases if proband is the less commonly affected sex
    • 3) Increases with more severe phenotype
    • 4) Decreases is lesser degrees of relatedness
  9. What are the true definitions of "nature" and "nurture"?
    • Nature: genetics
    • Nurture: environment
  10. Are monozygotic twins different b/c of genetics or environment?
    Environment b/c from same fertilized egg = same genes
  11. Are dizygotic twins different b/c of genetics or environment?
    More genetics, 50% just like any other kid
  12. What is Concordance?
    When twins share a trait
  13. What is discordance?
    When twins do not share a trait
  14. What does Heritability tell us?
    The higher the number, the more chance the trait is a reflection of genetics
  15. What is the Heritability equation?