PATHOLOGY

PATHOLOGY MCQ

GENETICS AND DISEASE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In humans, hemophilia is an X-linked recessive trait. If a man and a woman have a son who is affected with hemophilia, which of the following is definitely true?
A
The mother carries an allele for hemophilia
B
The father carries an allele for hemophilia
C
The father is afflicted with hemophilia
D
both parents carry an allele for hemophilia
Explanation: 

Detailed explanation-1: -If the son gets his mother’s X chromosome with the hemophilia gene he will have hemophilia. 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.

Detailed explanation-2: -A female can also have hemophilia if she inherits hemophilia alleles from both of her parents or if she inherits one hemophilia allele and her other X chromosomes is missing or does not work properly.

Detailed explanation-3: -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-4: -Hemophilia Inheritance Patterns If the mother has one altered factor gene and the father does not have hemophilia, each son has a 50% chance of having hemophilia and each daughter has a 50% chance of having one altered factor gene, causing her to be a carrier or have hemophilia.

Detailed explanation-5: -Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern . The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes . In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition.

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