What does low level DNA mean?
“Low level DNA” refers to a small amount of genetic material detected in a sample.
This can occur where only a limited number of cells are present, where biological material has degraded over time, or where DNA has been transferred indirectly. Low level DNA is common in forensic casework, particularly on clothing, shared surfaces, and items handled by multiple people.
Results based on low quantities of DNA are often more complex to interpret. The DNA may be incomplete, mixed with material from other individuals, or affected by background DNA already present on the item.
Laboratory analysis can still produce findings from low level DNA, but the interpretation may rely more heavily on analytical decisions, statistical modelling, and assumptions about contributors.
Low level DNA is also more susceptible to transfer and contamination. It may arise from indirect contact, everyday handling, or movement of biological material between people and objects.
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