RFLP

RFLP, or restriction fragment length polymorphism, is a molecular technique used to detect variation in DNA sequences by monitoring fragment lengths produced after digestion with restriction enzymes. DNA from different individuals contains slightly different sequences, which can create or abolish restriction sites or alter fragment sizes. When the DNA is cut and the fragments are separated by size, the resulting pattern of fragments—often visualized as a banding pattern on a gel—differs between individuals or samples, enabling polymorphism detection.

Typical RFLP analysis involves several steps: extraction of genomic DNA; digestion with one or more restriction enzymes; separation of fragments by gel electrophoresis; transfer of DNA to a membrane (Southern blot); probing with labeled DNA probes complementary to a region of interest; and visualization of the band pattern.

RFLPs arise from sequence variations that create or remove restriction sites or from insertions/deletions that change fragment lengths. The polymorphism is detected as a change in the size of restriction fragments between samples for a given locus.

RFLP has been used in genetic mapping, paternity and forensic testing, and population genetics. In forensics, it contributed to early DNA profiling before PCR became widespread. In breeding and research, it remained a standard method for locus analysis and linkage studies.

RFLP analysis requires relatively high-quality DNA and is time-consuming and labor-intensive; it also generally has lower throughput. With the rise of PCR-based methods and sequencing, RFLP has largely been superseded for routine typing, though it remains foundational in the history of genetic polymorphism analysis.