Question

Hemophilia is a sex-linked disorder that is caused by a defective gene on the X chromosome. What will be the pattern of inheritance of the offspring of a hemophiliac father?

Answer 1

Hemophilia is considered a sex-linked recessive disorder which means the disease does not occur if only one gene in a pair is abnormal.

Inheritance pattern of the offspring of a father who has hemophilia and a mother who does not have hemophilia and is not a carrier:
- all sons will be born normal
- all daughters will be carriers

Inheritance pattern of the offspring of a father who has hemophilia and a mother who is a carrier:
- 25% chance of having a hemophiliac son
- 25% chance of having a son with no hemophilia
- 25% chance of having a daughter who is a carrier
- 25% chance of having a hemophiliac daughter