PATHOLOGY MCQ
GENETICS AND DISEASE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Because men with hemophilia don’t often live to reproductive age.
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Because hemophilia is a Y-linked trait.
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Because women with hemophilia live a long time.
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Women must have lots of testosterone to have hemophilia.
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Detailed explanation-1: -These disorders affect males more often than females because females have an additional X chromosome that acts as a “back-up.” Because males only have one X chromosome, any mutation in the factor VIII or IX gene will result in hemophilia.
Detailed explanation-2: -This means that males only have one copy of most of the genes on the X chromosome, whereas females have 2 copies. Thus, males can have a disease like hemophilia if they inherit an affected X chromosome that has a mutation in either the factor VIII or factor IX gene.
Detailed explanation-3: -Since males have only a single copy of any gene located on the X chromosome, they cannot offset damage to that gene with an additional copy as can females. Consequently, X-linked disorders such as Hemophilia A are far more common in males.
Detailed explanation-4: -In some cases, it is possible for a female to have a father with hemophilia and a mother who is a carrier, and thereby inherit an affected X chromosome from both parents. Such daughters would have hemophilia, which may be mild, moderate or severe.