RFLP (Restriction Fragment Length Polymorphism)
Definition
The first DNA profiling method used in forensic casework, developed by Alec Jeffreys in 1984. Restriction enzymes cut DNA at specific sequences, producing fragments whose lengths vary between individuals. The pattern of fragment lengths, visualised by Southern blotting, constitutes a DNA profile. Requires relatively large, intact DNA samples.
- Developed by
- Alec Jeffreys, 1984
- Visualisation method
- Southern blotting
- Sample requirement
- Relatively large, intact DNA
- Status today
- Superseded by PCR-based STR profiling
- Sub-field
- Forensic biology, DNA profiling history
Common questions
Why was RFLP eventually replaced by STR profiling in casework?+
RFLP needed comparatively large amounts of undegraded DNA and took days to weeks to process, while PCR-based STR typing works on tiny or partially degraded samples and returns results far faster, which made it far more practical for casework volumes and evidence conditions.
What is the significance of RFLP being the first DNA profiling method in casework?+
It established the basic principle still used today, that individual variation in DNA sequence produces a distinguishable pattern, and it was the method behind the first criminal cases in which DNA evidence secured a conviction and also exonerated a wrongly accused suspect.
Can RFLP results still be compared to modern STR profiles?+
No, the two methods target different types of genetic variation and produce incompatible data formats, so old RFLP profiles from archived casework cannot be directly matched against modern STR databases without new testing.
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Explained in these topics
- History and Development of Forensic Biology
- Restriction Enzymes, Vectors, Ligation and Molecular CloningVariation in the length of DNA fragments produced by digestion of genomic DNA with a restriction enzyme, due to differences in the spacing between restriction...