Molecular Biology/Genetics USMLE Step 1 Practice Question
Genomic DNA from a child with pyruvate kinase deficiency identifies a mutation in the 3'-splice site of intron 3. The mRNA from the child's reticulocytes is used to produce cDNA. Primers flanking the exon 3/exon 4 border are used to amplify this region from the cDNA (RT-PCR). The products are separated by electrophoresis and compared to the RT-PCR products from normal reticulocytes (control). The results are shown below: Control shows 84 bp band, Patient shows 78 bp band. Which of the following mechanisms best accounts for the results of the splice mutation?
Answer choices
- ATrinucleotide expansion
- BExon skipping
- CMissense mutation
- DTwo-codon deletionCorrect answer
- EFrameshift mutation
- FIntron retention
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