Question

(a) Why is haemophilia generally observed in human males? Explain the conditions under which a human female can be haemophilic.
(b) A pregnant human female was advised to undergo M. T. P. It was diagnosed by her doctor that the foetus she is carrying has developed from a zygote formed by an XX-egg fertilized by Y-carrying sperm. Why was she advised to undergo MTP?

Answer 1

• Haemophilia is a sex-linked disorder. In haemophilia, the blood fails to clot when exposed to air and even a small skin injury results in continuous bleeding and can lead to death from the loss of blood.

The recessive X linked gene for haemophilia shows characteristic criss-cross inheritance. It's a single gene in male results and disease haemophilia, where is a woman needs two such genes for the same.

• MTP is the medical termination of pregnancy where the fetus is aborted because of a genetic disorder or severe complications which may arise during the parturition. Here in this case where zygote carries an XX egg then the ploidy of child will be more than 2n and it will have 47 chromosomes instead of 46 and it will result in a disease which is known as Klinefelter syndrome. This is a genetic disease which leads to the feminine characters in the male child. Therefore the doctor suggests MTP in such conditions.