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Biology LibreTexts

6: Pedigrees

  • Page ID
    • 6.1: Pedigree Analysis
      Pedigree charts are diagrams that show the phenotypes and/or genotypes for a particular organism and its ancestors. While commonly used in human families to track genetic diseases, they can be used for any species and any inherited trait.
    • 6.2: Inferring the Mode of Inheritance
      Given a pedigree of an uncharacterized disease or trait, one of the first tasks is to determine which modes of inheritance are possible and then which mode of inheritance is most likely. This information is essential in calculating the probability that the trait will be inherited in any future offspring. We will mostly consider five major types of inheritance: autosomal dominant (AD), autosomal recessive (AR), X-linked dominant (XD), X-linked recessive (XR), and Y-linked (Y).
    • 6.3: Sporadic and Non-Heritable Diseases
      Many diseases that have a heritable component, have more complex inheritance patterns due to (1) the involvement of multiple genes, and/or (2) environmental factors.
    • 6.4: Calculating Probabilities
      Probabilities in pedigrees are calculated using knowledge of Mendelian inheritance and the same basic methods as are used in other fields. The first formula is the product rule: the joint probability of two independent events is the product of their individual probabilities; this is the probability of one event AND another event occurring.