# Hemophylia(advanced pathophysiology) textbook mccance,K.L Huether 6TH ED)

Case Study 3

Please refer to Box 4-2 in the textbook.

Please look at the partial pedigree for the descendents of Queen Victoria, showing the appearance of hemophilia A in one of her sons (Leopold) and in his descendants. Leopoldas daughter, Alice of Athlone, had one hemophilic son (Viscount Trematon) and two other children, a boy and a girl, whose status is unknown.

What is the probability that her other son was hemophilic?

What is the probability that their daughter was a carrier? Or Hemophilic?

What is the probability that both children were normal?

2. This is the example of the assignment Case Study 3

Hemophilia is inherited as an X-linked recessive trait disorder that affects males and is transmitted/carried by females. The partial pedigree of Queen Victoria in our textbook 6th edition Box 4-3 has been reviewed for this case study.

The probability Queen Victoriaas son Leopold had hemophilia is 25%. When a mother is the carrier on an X chromosome and mates with a father unaffected by hemophilia there are four possible outcomes for each pregnancy. They can have a son without hemophilia, a daughter who is not a carrier, a son with hemophilia or a daughter who is a carrier. There is an equal chance of each of these outcomes with each pregnancy. Whether the sons have hemophilia or the daughters are carriers depends on which X chromosome they receive from the mother.

The probability of Leopoldas daughter being a carrier is 100%. When a father who has hemophilia mates with an unaffected by hemophilia there are two possible outcomes for their children. The sons will always receive an unaffected X chromosome from the mother and an unaffected Y chromosome from the father resulting in sons all without hemophilia. The daughters will always receive the hemophilia affected X chromosome from the father and an unaffected X chromosome from the mother resulting in daughters that are always carriers.

The probability of Leopoldas daughter having hemophilia is almost never. At least one of her two X chromosomes will have the appropriate genes.

The probability of Alice of Athloneas other two children being normal is 25%. There are four outcome possibilities. There can be a son without hemophilia, a daughter who is not a carrier, a son with hemophilia or a daughter who is a carrier. Again, with each pregnancy there is an equal chance of each of these outcomes. The male offspring has a 50% chance to have hemophilia or not. The female offspring has a 50% chance to be a carrier of hemophilia or not.