Hemophilia is an inherited sex-linked genetic blood disorder in which clotting factors (VIII or IX,depending on the variant of the disorder) are reduced or absent. It doesn't result in heavier bleeding, but in longer bleeding, since the clotting factors cannot adequately stanch the flow of blood. Depending on the severity and treatment, the lifespan of a hemophiliac can range from adolescence to old age. The gene is located on the X-chromosome. Since males only have one X copy, any occurrence of the mutation in males results in haemophilia. Females, however, have two copies of the X-chromosome, and the disease only shows up when both copies of the X-chromosome have the mutation. What can we do with this information? Let's start by writing the probability of having the mutation allele as p=0.0002. The probability that a female would acquire the disease is the probability of having the mutation allele on one X-chromosome and the mutation allele on the second X-chromosome. Mathematically, the probability of a female having the disease (H) is H=p*p, which is H=0.00000004. The following questions require you to use this biological knowledge to calculate the probability of the disease. Use G to denote a normal allele, and g to denote the mutation allele.
1) Prince Albert did not have haemophilia, which we can denote as G. QueenVictoria was a carrier but did not have the disease herself, which we can denote as Gg. Given this, determine the probability that a child of theirs would be a boy and be a haemophiliac. (Hint: you will need to first find the probability of being a boy and then the probability that the boy will be a haemophiliac).
2) Queen Victoria had nine sons children. Three of her nine children either had hemophilia (Leopold) or were carriers (Alice and Beatrice). What's the probability that one of her four sons would have hemophilia? (Hint: don't include the probability of being male in this calculation, and make sure to set it up as (g,G,G,G) or (G,g,G,G) or (G,G,g,G) or (G,G,G,g))