Inheritance Patterns

Autosomal dominant inheritance

Autosomal Dominant Inheritance

  • Affected relatives every generation
  • Males and females have equal chance of passing on mutation
  • 50% risk to children

Autosomal recessive inheritance graphic

Autosomal Recessive Inheritance

  • May be only one generation affected
  • Both parents must be carriers of the mutation
  • 25% risk to children

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X-linked Inheritance

  • No male-to-male transmission
  • Though rare, females can be affected if they inherited two mutations
  • Many female carriers (one mutation) will have no mutations; those that do have milder symptoms than seen in males
  • Risk for inheriting an X-linked mutaiton:
    • 100% for daughters of affected fathers to be affected
    • 100% for sons of affected mothers to be affected
    • 50% for daughters of carrier mothers to be carriers
    • 50% for sons of carrier mothers to be affected
    • 0% for sons of affected fathers to be affected

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Complex Inheritance

  • Clustering of biologically related conditions in the family
  • Risk estimates based primarily on empiric data
  • The chance of developing a complex trait depends on several factors, including:
    • The number of relatives affected with a condition (or related conditions)
    • How closely one is related to the affected individual(s)
    • Similarity of the shared environment
    • The location of disease or body system involved
    • Severity of the condition in the affected relative
    • The age at onset in the affected family member
    • The sex of the affected family member