Hemophilia A is a X-linked recessive disorder characterized by dysfunctional blood clotting, due to a mutation in the gene for the clotting component, Factor VIII. Julie's brother has hemophilia A, but neither Julie nor anyone else in her family shows symptoms of the disorder.

(i) If Julie has a son, what is the probability that he will have hemophilia?

(ii) Would this probability be different if Julie's husband had hemophilia? Explain.

Imagine that there is a DNA-based marker on the X chromosome that is 10 cM away from the gene for Factor VIII. This marker has two alleles, designated M1 and M2, that can be distinguished by a simple analysis of the DNA in a blood sample. The genotype of Julie for this marker is M1/M2, the genotype of her mother is M1/M2, the genotype of her father is M2, and the genotype of her brother is unknown.

(iii) Draw pictures to illustrate all possible arrangements of the given alleles for both of Julie's X chromosomes. Be sure to account for both of the DNA marker alleles and both alleles of the gene associated with hemophilia A.

(iv) What is the probability of each of the above arrangements occurring?

(v) Given that Julie is a carrier, which of the above arrangements must be correct?

(vi) Given that Julie is a carrier, what is the probability that she will have a son that carries the M2 allele and has hemophilia?