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Inheritance and Pedigrees

Tracking Disease through Generations

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Patterns of Inheritance

Believe it or not, there are very identifiable patterns to the ways humans inherit single gene traits. (Remembering that polygenic -multiple gene- traits are far more complicated)��

  • Autosomal Dominant�
  • Autosomal Recessive�
  • Sex - Linkage

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Autosomal Dominant

  • If you inherit just one copy of the affected gene then you will have the disease.�
  • In other words, if you are heterozygous OR homozygous for the disease, you get it.

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Autosomal Recessive

  • In order to have the disease, you MUST inherit TWO copies of the affected gene.�
  • In other words, you MUST be homozygous for the disease in order to have the disorder. �
  • Heterozygous = Carrier

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Sex - Linkage

  • Refers to disorders conferred by mutations on EITHER sex chromosome (X or Y)�
  • Women: you must inherit two affected X chromosomes in order to have the disorder�
  • Men: you only need your X or your Y to be affected for you to have the disease

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Pedigrees

AKA = Family trees used to track the inheritance of a genetic disorder

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Pedigrees

Reading a Pedigree:�

  • Square = Male��
  • Circle = Female
  • Filled = Affected��
  • Half = Carrier��
  • Empty = Healthy

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Figure it out...

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Recognizing phenotypes

Widow’s Peak (dominant)

Hitchhiker’s thumb (recessive)

Dimples (dominant)

Tongue Rolling (dominant)

Free earlobes (dominant)

PTC tasting (dominant)