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School of Medicine

Determining Genetic Risk


Determining Genetic Risk is an interactive web program designed to teach students in a clinical genetics course to:

1. Interpret a family history and draw a pedigree using symbols to indicate:

  • Males, females, and fetuses
  • Probands
  • Affected family members

2. Determine, from looking at the pedigree, what the mode of inheritance is likely to be:

  • Autosomal Recessive
  • Autosomal Dominant
  • X-linked Recessive
  • X-linked Dominant
  • Mitochondrial

3. Calculate risk for specific family members.

The Importance of a Pedigree

Recording a family history as a pedigree diagram clarifies and organizes verbal information. Using symbols to denote the family history can also take less time than writing it down as text.

For instance, compare this description to a pedigree diagram :

A 20-year-old female comes to clinic with questions about her risk for carrying the gene for Duchenne Muscular Dystrophy (DMD). Her brother died with DMD. Her mother also has two brothers who died with DMD, and they believe her grandmother, had a brother with DMD also.


pedigree example

If you look at this pedigree diagram, what do you notice?

  • The affected individuals are all males.
  • The affected males are all related through females.
  • Given these facts, what inheritance pattern might come to mind?
  • Would you have been able to determine the inheritance pattern as easily from the text family history?

A family history pedigree can be used as a tool to help:

  • determine the pattern of inheritance
  • make a medical diagnosis
  • decide which family members need testing
  • calculate risk for various family members

To review a case click on a link in the above menu.