RFLP

The human genome contains a wide variety of DNA sequences that are present in multiple copies. The exact number of copies of each repeated sequence varies with each individual. RFLP is a technique for looking at the variation in the copy number of these repeats by cutting genomic DNA with specific restriction nucleases, separating them on an agarose gel and then hybridizing probes specific for different repeated sequences. The information obtained can then be used for identification purposes.

AFLP(Amplified Fragment Length Polymorphism)

Similar to RFLP, the difference is in the way the fragments are produced. In RFLP, regions of repetitive genomic DNA are lit up with a probe after all the DNA has been cut into small pieces by a restriction enzyme. In AFLP, the fragments are produced by PCR amplification using unique sequences that flank the repetitive region. Again, since each one of us has a particular repetitive set of regions, which contain a variable number of repeats, individuals can be identified by the size of the different fragments. The advantage of AFLP over RFLP is that less material is needed to identify the individual.

SSCP (Single Stranded Conformational Polymorphism)

Unlike Southern blot analysis, SSCP relies on the migration characteristics of single stranded DNA, which is very dynamic in its kinetic action This structure allows it to either migrate faster or slower through a gel. Some researchers rely on this technique to give them information about single base substitutions that are known to be associated with disease.