Simply Forensic Reference Library
Allelic Drop-In
Forensic DNA & Genetics
Definition. A detected allele-like signal that is not explained by the assumed contributors or known artefacts and may arise from sporadic contamination or other unexplained mechanisms.
How the term is used
Before considering drop-in, analysts assess controls, stutter, spectral artefacts, replicate data and possible additional contributors.
Forensic example
A weak isolated peak appears in one PCR amplification but not another.
Interpretation limitation
Do not label every minor peak as drop-in without evaluating alternative explanations.
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.