BIOL 111

Genetic Problems Involving Sex-linkage

1. Bob and June both come from families with color blindness. June's mother was color blind and so was Bob's father. Neither June nor Bob themselves are color blind. They have a two year old boy and a 9 month old girl. What is the chance that their son is color blind? What is the chance that their daughter is color blind?
2. Another couple, Job and Bun, are planning to have children. Bun's father is color blind and Job is color blind. Bun has consulted with a genetic counselor because she is worried that all her children are doomed to be color blind. What is the chance that a child born to them will color blind?
3. Penelope is concerned that she may have a child with hemophilia. Her husband, Frank, has no history of hemophilia in his family, but Penelope's grandfather on her mother's side had hemophilia and died at 27. (See the pedigree below.) Should Penelope be concerned? If she has a daughter, what is the chance that she will have hemophilia? If she has a son, what is the chance he will have hemophilia?
4. Fred is 20 with a gorgeous head of hair. A friend, who knows him and his family very well, has just told Fred that he will get male pattern baldness for sure. Fred is worried. His hair is his life and to lose it would be terrible. As it turns out Fred's mother has male pattern baldness, but his father does not. His grandfather on his father's side also has male pattern baldness. Is Fred doomed to be bald? If not, what are the chances that he will be bald?

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