PATHOLOGY

Detailed explanation-1: -There are no genes for clotting factors on the Y chromosome. This means that males only have one allele for factor VIII and one allele for factor IX. Thus, if a male has a hemophilia allele on his only X chromosome, he will have the disorder.

Detailed explanation-2: -However, all daughters of a man with hemophilia are considered obligate carriers of hemophilia because they must receive the affected X chromosome from their fathers to be female, and they can pass the gene to their sons. A female with the hemophilia gene is called a hemophilia carrier.

Detailed explanation-3: -If he inherits his mother’s other X chromosome, he will have normal blood clotting. So a carrier’s son has a 50% chance of having hemophilia. A baby girl will inherit an X chromosome with a dominant gene for normal blood clotting from her father. So the daughter will not have hemophilia.

Detailed explanation-4: -Hemophilia is an X-linked recessive hereditary disorder that classically affects males due to the presence of only one X chromosome in males. Females are usually carriers due to the presence of counterpart X chromosome, but many times manifestations of hemophilia are seen in heterozygous carrier females.

Detailed explanation-5: -Hemophilia Carriers A female who inherits one affected X chromosome becomes a “carrier” of hemophilia. She can pass the affected gene on to her children. In addition, a female who is a carrier sometimes can have symptoms of hemophilia.