DNA Profiling

An early form of DNA profiling, rarely used today, is based on VNTRs, or "variable number of tandem repeats." VNTRs requires extensive sample processing: The DNA is chopped up with restriction enzymes, separated by size, and probes are applied to the fragmented DNA to view only the relevant DNA pieces. In the DNA of two different individuals, different spacing between two cut sites for the restriction enzymes gives a unique pattern of DNA size fragments, called "restriction fragment length polymorphisms," or RFLPs.