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Assessment and "In Vitro" Repair of Damaged DNA Templates

NCJ Number
Jack Ballantyne
Date Published
93 pages
This study first examined the types of DNA damage encountered in forensically relevant strains of DNA and then attempted to repair the damage using in vitro repair systems.
Findings indicated that the main causes of the damage resulting in DNA profile loss were single and double strand breaks and modifications to the DNA structure. The in vitro DNA repair attempts, which focused on single strand break/gap repair and translesion synthesis assays, resulted in genetic signatures being recovered from previously intractable samples. Research methods used to examine types of DNA damage focused on the detection of damage caused by exogenous, environmental sources, UV irradiation, heat, humidity, and microorganism growth. Physiological DNA samples, both hydrated and dehydrated samples were subjected to varying doses of UVC and the extent of damage was assessed by gel electrophoresis and then by amplifying the sample using a standard autosomal STR (short tandem repeat) multiplex. The author also examined the effects of various laboratory storage conditions on the DNA in bloodstains. Bloodstains were either allowed to dry overnight or were placed in storage while still wet. Both sets of bloodstains were stored at room temperature for up to 4 years. Results indicated that bloodstains that were allowed to dry prior to storage were stable and showed no signs of degradation or loss of genetic profile. Tables, references, appendixes