As previously mentioned, ARMS is noted for being highly specific for a normal primer and a mutant primer. ARMS is based on allele-specific priming of the PCR process which, after the process is complete, can reveal the genotype of the patient in question. The process requires normal primers, common primers and mutant primers. The normal primer is matched at its 3’ end to the normal nucleotide and is mismatched at its 3’ end to the mutant nucleotide. The reverse happens as well; the mutant primer is matched at the mutant nucleotide and mismatched at the normal sequence.
A mismatched 3’ end of a the primer prevents nucleotide expansion during DNA synthesis in a PCR reaction, and, consequently, no reaction occurs. In an ARMS reaction, DNA is split into two aliquots, one undergoes reaction with normal primers, while the other with mutant primers. The formation of a product is measured by gel electorphoresis. If a product is formed when the normal primers are used, then the DNA sample used came from a patient who is homozygous for the normal nucleotide. If products are present in both reactions, the patient is heterozygous. Lastly, if only one PCR product exists from the mutant primers, then the patient is homozygous for the mutation.
Because of ARMS' ability to detect single nucleotide polymorphisms (SNPs) in heterozygote patients, the technique has been increasingly popular. A few studies have been produced that examine mutations in patients where ARMS has been used.