Identification Through DNA Analysis in Criminal and Family-Relatedness Investigations

This chapter discusses the identification through DNA analysis in criminal and family-relatedness investigations. Genetic polymorphisms in chromosomal DNA revolutionized the field of identification testing and radically improved the level of certainty in conclusions issued by labs performing parentage or forensic testing. The variability in DNA discovered were associated with the human myoglobin gene. DNA "fingerprints" could be visualized in human genomic DNA using the then-rather-standard molecular technique known as restriction fragment length polymorphism analysis. The highly variable DNA markers visualized through RFLP analysis group exhibited a molecular structure consisting of a short sequence of nucleotides that was tandemly repeated a variable number of times along a length of chromosome. If chromosomal DNA is digested with a restriction enzyme that cuts in the DNA flanking the tandem array, or if polymerase chain reaction (PCR) amplification is performed using primers designed to recognize sites in the flanking DNA, products will be produced whose length is proportional to the number of repeats in the array. Electrophoresis can then be used to separate and, in the case of RFLP analysis, a Southern blot hybridized under stringent conditions to a complementary labeled DNA probe will allow the VNTR alleles in the DNA sample to be visualized. If the VNTR alleles are produced using PCR, allelic products will accumulate to levels that can be easily visualized using generic DNA stains or through modification of one or both primers used to direct the amplification. © 2010