Molecular Biology of the Gene 7th Edition by Richard Losick, James Watson, Michael Levine, Tamara Baker, Alexander Gann

Exercise 13

A deficiency in factor VIII causes hemophilia A, a blood disorder. Researchers studying hemophilia A evaluated the DNA from an affected patient and the patient's unaffected mother. They analyzed the 186-kb-long factor VIII gene that includes 26 exons (see Chapter 14). After digesting the genomic DNA with KpnI or SstI and separating the products by gel electrophoresis, the researchers probed the DNA with a radiolabeled cDNA probe that binds the factor VIII gene in a region that includes exons 14-26. The size of the fragments and the corresponding exon(s) are shown on the right of autoradiograms. The researchers conclude a transposon inserted into one of the exons of the factor VIII.
A. Describe the differences between the patient and mother S st I digest results. Be specific.
B. Describe the differences between the patient and mother KpnI digest. Be specific.
C. Propose an hypothesis explaining the observed differences including what exon of the factor VIII gene contains the transposon.
Data adapted from Kazazian Jr. et al. (1988. Nature 332 :164-166).