Rapid Quantification of DNA Samples Extracted from Buccal Scrapes Prior to DNA Profiling

DNA samples within our laboratory are routinely quantified to ensure that the optimal amount of DNA is analyzed by fluorescence-based multiplex analysis of amplified short tandem repeat (STR) loci. Routine quantification is by a dot blot hybridization assay using a probe complementary to the human D17Z1 locus (5,6), and 2 ng of human chromosomal DNA are added to the polymerase chain reaction (PCR) solution. The advantage of this technique is that it enables DNA samples containing less than 1 ng/μL to be quantified, and it is specific for target human DNA rather than total DNA within the sample, which may include significant amounts contaminating nonhuman DNA. However, the technique is relatively slow and labor-intensive to perform. Furthermore, it is not amenable to automation, a prime consideration with high-throughput studies. To address these issues, a sensitive method of DNA quantification using a fluorescent dye was developed.