Amplification refractory mutation system

This example of amplification refractory mutation system (ARMS) PCR shows how this technique can be used to distinguish between an individual who is homozygous for a normal gene and individuals homozygous or heterozygous for mutation in that gene. In this case separate primers are designed to match the normal gene sequence or the mutant gene sequence. The DNA sequences in red represent the patient DNA; the sequences in green are the primers. The box shows the mutant base and the corresponding altered base on the mutant primer.
A an agarose gel is run with the PCR products, and the presence of a band shows whether the normal or mutant DNA sequence was present.
Lanes 2 and 3: Individual with the normal gene; only the normal primer gives a PCR product.
Lanes 4 and 5: Individual homozygous for the mutation; only the mutant primer gives a PCR product.
Lanes 6 and 7: Individual heterozygous for the mutation; both the normal and mutant primers give PCR products.
Note: A control DNA product was present in all lanes, verifying that the PCR reaction worked.