Chapter 10, Problem 31P

For the following crosses, determine as accurately as possible the genotypes of each parent, the parent in whom nondisjunction occurs, and whether nondisjunction takes place in the first or second meiotic division. Both color blindness and hemophilia, a $\text{blood-clotting}$ disorder, are $\text{X-linked}$ recessive traits. In each case, assume the parents have normal karyotypes ( $\text{see Table 10}\text{.2}$).

A man and a woman who each have $\text{wild-type}$ phenotypes have a son with Klinefelter syndrome (XXY) who has hemophilia.

A man who is color blind and a woman who is wild type have a son with Jacob syndrome (XYY) who has hemophilia.

A $\text{color-blind}$ man and a woman who is wild type have a daughter with Turner syndrome (XO) who has normal color vision and blood clotting.

A man who is color blind and has hemophilia and a woman who is wild type have a daughter with triple X syndrome (XXX) who has hemophilia and normal color vision.