Question:medium
Prenatal diagnosis of hemophilia is best done by:
Prenatal diagnosis of hemophilia is best done by:
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Known single-gene mutation in fetal DNA is best confirmed by direct amplification.
Updated On: Jun 24, 2026
- PCR
- Linkage analysis
- Cytometry
- Microarray
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The Correct Option is A
Solution and Explanation
Hemophilia is a textbook X-linked recessive condition caused by mutations in a single clotting-factor gene, factor VIII in type A and factor IX in type B. So prenatal diagnosis boils down to finding that mutation in fetal tissue obtained by chorionic villus sampling or amniocentesis.
The cleanest way to do that is to amplify the gene region with PCR and read the mutation directly. For severe hemophilia A, PCR can even pick up the common intron 22 inversion. Direct PCR mutation detection is fast, specific and does not depend on other family members being available, which is why it is the test of choice.
The other options fall short. Linkage analysis is an indirect, marker-tracking method reserved for situations where the family mutation has not been characterized, and it can be tripped up by recombination, so it is second-line. Cytometry quantifies cells and surface proteins, useless for spotting a coagulation-gene mutation. Microarray is geared to copy-number and large structural changes, not the small mutations that cause hemophilia. Direct PCR wins.
\[\boxed{\text{PCR}}\]
The cleanest way to do that is to amplify the gene region with PCR and read the mutation directly. For severe hemophilia A, PCR can even pick up the common intron 22 inversion. Direct PCR mutation detection is fast, specific and does not depend on other family members being available, which is why it is the test of choice.
The other options fall short. Linkage analysis is an indirect, marker-tracking method reserved for situations where the family mutation has not been characterized, and it can be tripped up by recombination, so it is second-line. Cytometry quantifies cells and surface proteins, useless for spotting a coagulation-gene mutation. Microarray is geared to copy-number and large structural changes, not the small mutations that cause hemophilia. Direct PCR wins.
\[\boxed{\text{PCR}}\]
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