Question

Hemophilia is more common in males because it is a
A. Recessive character carried by Y chromosome
B. Dominant character carried by Y chromosome
C. Dominant trait carried by X chromosome
D. Recessive trait carried by X chromosome

Answer 1

Hint: Haemophilia is a blood condition that is inherited from both parents. Because clotting factors are missing in the blood of patients with haemophilia, blood does not clot properly. The X-chromosome contains the defective gene that causes haemophilia. There are two forms of haemophilia: Haemophilia type A and Haemophilia type B.

Complete answer:
Option A: Because females have an extra X chromosome that functions as a "back-up," these illnesses affect males more frequently than females. Because males only have one X chromosome, haemophilia is caused by a mutation in the factor VIII or IX gene.
So option A is not correct.
Option B: Hemophilia is a recessive sex-linked condition. The X chromosome contains the defective gene that causes haemophilia.
So option B is not correct.
Option C: These disorders affect males more commonly than females because females have an additional X chromosome that serves as a "back-up." Because males only have one X chromosome, a mutation in the factor VIII or IX gene causes haemophilia.
So option C is not correct.
Option D: The X chromosome mutation that causes haemophilia is handed down to offspring as a recessive X-linked genetic condition. Because male offspring only inherit one X chromosome, haemophilia is more common among them.Both an X and a Y chromosome are found in males, whereas females have two X chromosomes. Because males only have one X chromosome, if that chromosome has the mutation, they will develop haemophilia symptoms.In females, however, the inheritance of one defective X chromosome does not normally induce symptoms since they usually inherit another normal X chromosome.A female can develop haemophilia if she is born to a female carrier and a haemophiliac man, however this is extremely unusual.

So option D is the correct answer.

Note:
Patients with Haemophilia B Leyden suffer episodes of heavy bleeding during childhood, but after puberty, they have fewer bleeding difficulties.
Haemophilia type C is the most uncommon form of the disease. A blood-clotting factor XI deficiency can occur and is characterised by bleeding episodes following tooth extractions or other comparable operations.
Acquired haemophilia is a non-inherited form of haemophilia produced by the immune system wrongly attacking blood clotting proteins.