Simply Forensic Reference Library

DNA Degradation Index

Forensic DNA & Genetics

Definition. A quantitative PCR indicator comparing assay targets of different sizes to assess fragmentation or related differential amplification of DNA.

How the term is used

Many kits use a ratio involving a shorter and a longer human DNA target, but the calculation is assay dependent.

Forensic example

A high degradation index may predict reduced amplification of longer STR fragments.

Interpretation limitation

It is not a direct measurement of the number of breaks in each DNA molecule.

References and further reading

SWGDAM guidelines for forensic DNA analysis. The explanation and example are original educational summaries; consult the cited material and current laboratory guidance for authoritative application.

Related guide: DNA Degradation Index in forensic practice.

Related glossary terms

Allelic Drop-InA detected allele-like signal that is not explained by the assumed contributors or known artefacts and may arise…Explore term Allelic DropoutFailure to detect an allele that is present in the DNA of a contributor, often because of stochastic…Explore term Analytical ThresholdA validated signal threshold, commonly expressed in RFU, above which electropherogram peaks are sufficiently distinguishable from analytical noise…Explore term Combined Probability of InclusionAn estimate of the proportion of a specified population that would not be excluded as a possible contributor…Explore term

Related articles

How the Degradation Index and DNA’s ‘Story’ Can Improve Forensic ProfilesNew research shows that while the DNA Degradation Index (DI) is a valuable tool for assessing degraded DNA,…Read article