Question

The most common form of hemophilia is a defect in blood clotting factor VIII, which is caused by a mutant form of a gene on the X chromosome. Boys who inherit that mutation from their mother suffer from uncontrolled bleeding. Girls carrying one copy of this mutation have near normal blood clotting. Uncommonly, a girl is born with hemophilia even though both parents have normal phenotypes. Which of the statements might explain hemophilia in a girl born to parents with normal blood clotting phenotypes?

Answer 1

Answer:

Nondisjunction during sperm arrangement and formation brought about her getting no sex-chromosome from her dad and an X chromosome from her mom, she is XO.

Explanation:

Nondisjunction during sperm arrangement and formation brought about her getting no sex-chromosome from her dad and an X chromosome from her mom; she is XO.  

It is on the grounds that her mother happens to be a carrier of hemophilia and she transferred that mutant allele to her daughter and due to the fact that she did not get any sex-chromosome from her dad.

However, such mutant (X) communicates and expresses itself and she is hemophilic.

This (X) is not express in her mother because she possesses a recessive trait; as such it appears in the hom8zygous state.