Question

when running the gel electrophoresis Why would the band pattern be different in the tumor DNA than the normal samples?

Answer 1

DNA obtained from normal patient cells will not have the restriction enzyme site and therefore the amplified DNA will not be cut and will appear as one band. The patient DNA from the tumor sample has a mutation at a particular site and therefore the tumor PCR amplified DNA will be cut to yield two DNA fragments. The peripheral blood and non-tumor patient DNA will have the same pattern where there are three bands due to the combined DNA patterns from the normal gene and the mutant gene.