The recessive gene for hemophilia is located on the X chromosome. The girl’s father is healthy, the mother is healthy

The recessive gene for hemophilia is located on the X chromosome. The girl’s father is healthy, the mother is healthy, but her father was sick with hemophilia. A girl marries her husband for a healthy young man. What about their future children and grandchildren?

H – healthy

h – hemophilia

P: XHXh (women) x XHY (husband)

G XH, Xh XH, Y

F1 XHXH healthy d., XHXh healthy d, XHY healthy m,

hemophilus XhY, m.

Answer: children: 75% are healthy, 25% are sick with hemophilia;

grandchildren: all healthy (both sexes), except those from a daughter who carry the gene (XHXh) – 25% chance of a boy with hemophilia (XhY)