The Use of the Polymerase Chain Reaction and the Detection of Amplified Products

The most polymorphic genetic markers are DNA regions composed of variable number tandem repeats (VNTRs) (1 ,2 ). Detection of the various VNTRs is possible by restriction fragment-length polymorphism (RFLP) analysis using the Southern blot procedure (3 ). However, this procedure is time-consuming and requires an isotopic assay to achieve the sensitivity necessary to detect VNTR alleles in samples containing as little as 10–50 ng of human DNA (4 ). The inability of RFLP technology to resolve discretely the alleles of VNTR loci also is a limitation. Where only limited quantities of DNA are available, or only single copy loci are to be analyzed, the DNA profile may be too weak to be detected with general RFLP methodology.