DNA is characteristic for each person. Fragments that have the same locus on chromosomes may differ in the sequence of bases. Unique character of genetic material makes it similar to fingerprint and enables identifying persons.

One of the more often used method in RFLP analysis (restriction fragment length polymorphism). DNA of a person is cleaved by restriction enzymes. Then fragments are segregated by gel electrophoresis. Electrophoresis leads to distribution depening on length, the shorter the fragments the quicker the move. Afterwards probes are added. The unique pattern is a result of different arrangement of sites cut by enzymes. Alteration of one base prevent the sequence for being cleaved. As a result if it is the fragment complementary to probe it will have different position because it’s longer.

RFLP analysis play a significant role among others in diagnosing and gene mapping.