U.S. flag

An official website of the United States government, Department of Justice.

Quantifying and Qualifying the Influence of Standard Laboratory Procedures on Aged, Degraded, and/or Low Copy Number DNA

NCJ Number
309917
Date Published
2024
Length
106 pages
Annotation

The objectives of the research presented in this report were to evaluate and develop methods that show promise for increasing the net yield of DNA and its purity through the following efforts: evaluation of DNA loss during its extraction and purification against standards; exploration of means to mitigate DNA loss and/or further damage to the molecules in the standards; and further improvement and/or development of novel methods to remove PCR inhibitors from DNA elutes and/or subdue their influences within the forensic workflow.

Abstract

The analysis of aged, degraded, and/or low copy number (LCN) DNA is complicated largely by: (1) the presence of modern contaminating DNA, (2) the co-extraction of impurities (PCR inhibitors) along with DNA, and (3) the degree of damage accumulated by endogenous DNA post-mortem or from the time of deposition of the biological material.  These problems make the analysis of DNA from aged, degraded, and/or LCN sources far more challenging than working with modern DNA.   

Objectives of our research are to evaluate and develop methods that show promise to increase the net yield of DNA and its purity.  These include: (1) evaluating DNA loss during its extraction and purification against standards (Phase I), (2) exploring means to mitigate DNA loss and/or further damage to the molecules in the standards (Phases I & II), and (3) further improving and/or development of novel methods to remove PCR inhibitors from DNA elutes and/or subdue their influences within the forensic workflow (Phase III).   Moreover, there are still several poorly understood aspects of how aged, degraded, and/or LCN DNA “behaves” during routine laboratory methods and, critically, whether some or all those behaviors truly differ from that of modern contaminating DNA.  

Moreover, there are hypotheses that newly observed damage patterns from ancient & endogenous DNA molecules are consistent and, thus, predictable.  If these hypotheses are accurate, presumably there would be measurably different expectations for the behavior of – and damage accrued in – modern exogenous contaminating DNA due to the reduced time since creation and deposition of the biological material.  To be clear, if the damage patterns observed in contaminating DNA mirror those routinely observed in authentic aged and degraded DNA, then damage patterns cannot be a used as a reliable means by which to discriminate between contaminating and endogenous DNA.  

Our proposed research employs state-of-the-art technology for the quantification and/or qualification of DNA using an Agilent Fragment Analyzer, CFX96 Touch™ Deep Well Real-Time PCR Detection System, and Illumina sequencing platforms.  The combination of these technologies will permit us to uniquely evaluate the above outlined issues and hypotheses in novel ways.  The observations made during our project will directly benefit forensic genetics, criminal justice, as well as the fields of ancient DNA (aDNA) and paleogenomics.

Date Published: January 1, 2024