Question

Women known to be heterozygous or carriers for the sex-linked recessive condition of hemophilia A were studied to determine the time required for their blood to clot. It was found that the time required for their blood to clot varied from individual to individual. The values obtained ranged from normal clotting at one extreme to clinical hemophilia at the other extreme. What is the MOST probable correct explanation for these findings?

A) Some women had only one X chromosome and it is inactive.

B) Some women had three copies of the X chromosome, which allowed them to make extra amounts of gene products for their X-linked genes.

C) The women with normal clotting times probably had a mother with hemophilia while those with abnormal clotting times probably had fathers with hemophilia.

D) Random X inactivation probably results in individuals with different proportions of cells in their bodies expressing the normal allele at the hemophilia locus.

Answer 1

C) The women with normal clotting times probably had a mother with hemophilia while those with abnormal clotting times probably had fathers with hemophilia.

In persons with the normal clotting blood time they are heterozygous in allele condition and only genes in one X chromosome is affected and the other X chromosome having normal genes is active and produce clotting factors and are having normal blood clotting times .

In persons with clinical hemophilia the genes in both the X chromosomes are recessive and does not produce the clotting factors and showing the clinical hemophilia.