International Journal of Legal Medicine

, Volume 126, Issue 6, pp 961–968

Effects of humic acid on DNA quantification with Quantifiler® Human DNA Quantification kit and short tandem repeat amplification efficiency

  • Seung Bum Seo
  • Hye Young Lee
  • Ai Hua Zhang
  • Hye Yeon Kim
  • Dong Hoon Shin
  • Soong Deok Lee
Technical Note

Abstract

Correct DNA quantification is an essential part to obtain reliable STR typing results. Forensic DNA analysts often use commercial kits for DNA quantification; among them, real-time-based DNA quantification kits are most frequently used. Incorrect DNA quantification due to the presence of PCR inhibitors may affect experiment results. In this study, we examined the alteration degree of DNA quantification results estimated in DNA samples containing a PCR inhibitor by using a Quantifiler® Human DNA Quantification kit. For experiments, we prepared approximately 0.25 ng/μl DNA samples containing various concentrations of humic acid (HA). The quantification results were 0.194–0.303 ng/μl at 0–1.6 ng/μl HA (final concentration in the Quantifiler reaction) and 0.003–0.168 ng/μl at 2.4–4.0 ng/μl HA. Most DNA quantity was undetermined when HA concentration was higher than 4.8 ng/μl HA. The CT values of an internal PCR control (IPC) were 28.0–31.0, 36.5–37.1, and undetermined at 0–1.6, 2.4, and 3.2 ng/μl HA. These results indicate that underestimated DNA quantification results may be obtained in the DNA sample with high CT values of IPC. Thus, researchers should carefully interpret the DNA quantification results. We additionally examined the effects of HA on the STR amplification by using an Identifiler® kit and a MiniFiler™ kit. Based on the results of this study, it is thought that a better understanding of various effects of HA would help researchers recognize and manipulate samples containing HA.

Keywords

DNA quantification Real-time PCR Short tandem repeat Humic acid PCR inhibitor 

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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Seung Bum Seo
    • 1
  • Hye Young Lee
    • 1
  • Ai Hua Zhang
    • 1
  • Hye Yeon Kim
    • 2
  • Dong Hoon Shin
    • 3
    • 4
  • Soong Deok Lee
    • 1
    • 4
  1. 1.Department of Forensic Medicine, College of MedicineSeoul National UniversitySeoulSouth Korea
  2. 2.DNA Analysis Laboratory, Division of Forensic ScienceSupreme Public Prosecutor’s OfficeSeoulSouth Korea
  3. 3.Department of Anatomy, College of MedicineSeoul National UniversitySeoulSouth Korea
  4. 4.Institute of Forensic Medicine, College of MedicineSeoul National UniversitySeoulSouth Korea

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