Pedigree

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Pedigree

• Not just a dog food company

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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

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Pedigree Symbols
Male
Female
Affected female/male (occasionally half shaded if
just a carrier)
Mating
Twins
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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
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Generation Indicators
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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

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Dominant Characteristics

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

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Recessive Characteristics

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

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Practice problems

• What is the most likely mode of inheritance below?

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

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Ginger Pedigree

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

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