Sex-linked Genes

The case of Queen Victoria

Hemophilia literally translates to blood loving. This is a description of a series of disorders where an individual has an inability to clot blood after a cut. In modern times, clotting factors may be administered to an afflicted individual, but a prior treatment involved blood transfusions. A very famous family had a genetic predisposition to hemophilia and due to the proliferative nature of this family, we have some statistical power to verify predictions on the probabilities of passing the disease state. Below is a partial pedigree for Victoria, Queen of the United Kingdom of Great Britain and Ireland and Empress of India. The filled in shapes represent individuals who suffered from hemophilia.

Victoria pedigree

  1. From the pedigree above, what can you say about this form of hemophilia with respect to dominance?
  2. From this pedigree, can you comment on the probable chromosome where the deficiency occurs?
  3. Assign genotypes for Prince Albert and Queen Victoria and perform a Punnet Square to illustrate if their offspring reflect your statements on dominance and chromosome location.
  4. Albert and Victoria were 1st cousins. Do you believe this had anything to do with the propagation of this disease? What does your Punnet Square tell you?
  5. Highlight the definitive carriers of the disease gene in the pedigree above.

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