Estimating the integrity of aged DNA samples by CE

Area of Science:

• Biochemistry
• Forensic Science
• Molecular Biology

Background:

• DNA degradation in aged samples poses challenges for genetic analysis.
• Accurate assessment of DNA integrity is crucial for reliable forensic and ancient DNA studies.

Purpose of the Study:

• To develop and validate a capillary electrophoresis (CE) method for analyzing DNA bases in aged specimens.
• To evaluate the relationship between DNA base integrity and the reliability of short tandem repeat (STR) typing.

Main Methods:

• Capillary electrophoresis with UV detection (CE/UV) was optimized for separating four canonical DNA bases and five related compounds.
• The method was applied to 16 aged samples, including Egyptian mummies and forensic specimens, comparing them to modern controls.
• Results were corroborated with traditional molecular techniques like agarose gel electrophoresis and UV spectrophotometry.

Main Results:

• Aged samples exhibited lower relative values of unmodified DNA bases (uDNAb) and more complex electropherograms compared to controls.
• Low uDNAb values were associated with failed or unreliable STR amplification.
• The CE method demonstrated selectivity, precision, accuracy, and sensitivity suitable for DNA primary structure analysis.

Conclusions:

• The developed CE/UV method effectively quantifies DNA bases, providing insights into DNA degradation.
• Reduced levels of uDNAb serve as a critical indicator of DNA quality and can predict the success of STR typing.
• This study proposes uDNAb quantification as a valuable quality control metric for genetic analysis of aged and degraded samples.