We inherit a copy of chromosome, one from father and one from mother for each of the 23 pairs of chromosomes, which indicate that we carry two copies of each VNTR locus, just like we have two copies of genes donated by our parents. At a particular VNTR site if you have the same number of sequence repeats, you are called homozygous at that site; if you have a different number of repeats, you are said to be heterozygous". VNTR sequences from different loci can be combined to create DNA fingerprint. Resulting patter of each individual is theoretically unique.

The diagnosis of DNA is a laboratory process which requires a number of sequential steps. There are many techniques used by various laboratories in analyzing DNA. However, the two most popular techniques used are Restriction fragment length polymorphism (RFLP), and polymerase chain reaction (PCR) using short tandem repeats (STRs). DNA extraction and purification is the first step involved in both the techniques. Techniques for DNA isolation depend on the type of sample used for isolation. Generally the sample may be treated with detergent that degrades protein and not affecting the DNA. To break the proteins and other cellular material, enzymes can be used. DNA can be separated using organic solvents form organic and non-organic material. By using the above methods the DNA is separated from the sample.

The two types of DNA Fingerprinting tests: RFLP and PCR/STR

Restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) amplification of short tandem repeats (STRs) are two main DNA tests widely used for DNA Fingerprinting. Other diagnostic methods exist, but they lack accuracy and precision.