The Application of PCR to Forensic Science

Abstract

Genetic characterization of biological materials for forensic purposes is being performed increasingly at the DNA level. Presently, the molecular biology approach generally used for individualization is the typing of variable number of tandem repeat (VNTR) loci (Nakamura et al., 1987) by restriction fragment length polymorphism (RFLP) analysis via Southern blotting (Southern, 1975). Although this approach is valid and reliable for forensic and paternity testing (Adams et al., 1991; Budowle et al., 1991c; Devlin et al., 1992; Giusti et al., 1986; Kanter et al., 1986), it has certain limitations. These include (1) a sufficient quantity of high molecular weight DNA (usually at least 50 ng) is required for RFLP analysis (Budowle and Baechtel, 1990); (2) isotopically labeled probes are required to obtain a high level of sensitivity of detection. The requirement of radioactive materials can impede the transfer of RFLP technology to some application-oriented laboratories; (3) RFLp analysis is laborious as well as time-consuming, requiring 4 to 8 weeks to obtain results on four VNTR loci; and (4) the RFLP technique cannot resolve unequivocally the alleles of most VNTR loci.