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Pedigree

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Pedigree Not just a dog food company Pedigree Some conditions/traits appear often in some families This is a clue that the condition/trait is genetic Looking at a ... – PowerPoint PPT presentation

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Title: Pedigree


1
Pedigree
  • Not just a dog food company

2
Pedigree
  • Some conditions/traits appear often in some
    families
  • This is a clue that the condition/trait is
    genetic
  • Looking at a persons family history can provide
    clues about that persons genotype

3
Pedigree Symbols
Male
Female
Affected female/male (occasionally half shaded if
just a carrier)
Mating
Twins
4
Pedigree Symbols
Why is it bad to mate with relatives? Disease
genes that are rare in the general population are
common within a family. Consanguineous
relationships increase the probability of
offspring having a rare recessive phenotype.
Mating
Offspring
Consanguineous Relationship
5
Generation Indicators
6
Terminology
  • Autosomal a non-sex chromosome (chromosomes
    1-22)
  • Autosomal dominant a dominant trait on an
    autosomal chromosome
  • Autosomal recessive a recessive trait on an
    autosomal chromosome

7
Dominant Characteristics
  • Found in every generation, and equally in males
    and females
  • Cannot skip generations
  • Affected individuals must have at least one
    affected parent

8
Recessive Characteristics
  • Can skip generations, and found equally in males
    and females
  • Can result from unaffected parents

9
Practice problems
  • What is the most likely mode of inheritance below?

10
  • Identify the genotypes of the following
  • I2
  • II3, II7
  • III1, III4, III10

11
Ginger Pedigree
  • Recessive or dominant?
  • Genotype of I1, I2, II1, II2, II3, III1, III2

12
  • Dominant or recessive
  • Which individuals can we be sure of their
    genotype?
  • What is the probability that IV2 is a carrier for
    alkaptonuria?
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