NCJ Number
248156
Journal
Forensic Science International Genetics Volume: 12 Dated: September 2014 Pages: 168-180
Date Published
September 2014
Length
13 pages
Annotation
This work assessed the use of repair enzymes to improve the short tandem repeat (STR) profile from artificially degraded DNA.
Abstract
The study found that the commercial PreCR repair kit of DNA repair enzymes may be useful for restoring STR profiles from damaged DNA; however, further work is needed in order to develop a generalized approach. The PreCR repair kit was tested on both purified DNA and native DNA in body fluid exposed to oxidizing agents, hydrolytic conditions, ultrviolet (UV) and ionizing radiation, and desiccation. The strategy was to restrict the level of DNA damage to that which yields partial STR profiles, so as to test for allele restoration rather than simple allele enhancement. Two protocols were used for allele restoration: a sequential protocol that uses the manufacturer's repair procedure and a modified protocol reportedly designed for optimal STR analysis of forensic samples. Allele restoration was obtained with both protocols, but the peak height appeared to be higher for the modified protocol determined by Mann-Kendall Trend Test. The performance testing of the PreCR repair enzymes was sporadic,, as it led to allele restoration as well as allele drop-out. In addition, allele restoration with the PreCR enzymes was compared with restoration by alternative, but commonly implemented approaches that use Restorase, PCRBoost, bovine serum albumin (BSA), and the Minifiler STR system. These alternative methods were also successful in improving the STR profile; however, their success depended on the quality of the template being analyzed. Based on this study, it is unclear which approach would be best for compromised forensic evidence. Further research is needed in this important area. 2 tables, 6 figures, and 35 references