Restriction fragment length polymorphism (RFLP) Genetic variation between individuals in DNA fragment sizes resulting from a difference in DNA sequence that affects the recognition sequence for restriction enzymes when cut by specific restriction enzymes. When DNA is digested by a particular enzyme the fragment sizes will differ depending on the presence or absence of the proper recognition sequence for the enzyme. Polymorphic sequences that result in RFLPs are used as markers on both physical maps and genetic linkage maps. RFLPs are usually caused by mutation at a cutting site.