Evaluation of Degradation in DNA from Males with a Quantitative Gender Typing, Endpoint PCR Multiplex

Evidentiary samples submitted to a forensic DNA laboratory occasionally yield DNA that is degraded. Samples of intact chromosomal DNA (both nuclear and mitochondrial) were subjected to a heating protocol to induce DNA degradation. The DNAs were then analyzed using a multiplex PCR assay that amplifies targets of low and high molecular weight on the X/Y and mitochondrial chromosomes. If degradation is random, the amplification of larger DNA targets should be more adversely affected by degradation than smaller targets. In nuclear and mitochondrial DNA from a male donor, exhibiting degradation, DNA quantity estimates based upon higher molecular weight amplicons (HMW) are significantly lower than estimates made using low molecular weight (LMW) Q-TAT amplicons. DNA degradation estimated using this approach correlated well with actual fluorescence associated with HMW and LMW STR alleles amplified from the same genomic DNA templates. Q-TAT is thus useful not only as a quantitation tool, but also as an indicator of template degradation.