Simply Forensic Reference Library

Heteroplasmy

Forensic DNA & Genetics

Definition. The presence of more than one mitochondrial DNA sequence variant within an individual or sample, including sequence or length heteroplasmy.

How the term is used

Mitochondrial DNA comparison and reporting use validated rules for assessing heteroplasmic differences and similarities.

Forensic example

Two maternally related samples share a major mtDNA sequence but show different proportions of a minor variant.

Interpretation limitation

Heteroplasmy is not automatically evidence of exclusion or unrelated maternal lineage.

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: Heteroplasmy 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

Forensic mtDNA Interpretation: Heteroplasmy, Haplogroups and EMPOP Database SearchesA comprehensive forensic mtDNA interpretation guide covering point and length heteroplasmy, sequence comparisons, EMPOP frequency estimates, maternal-lineage limitations…Read article Short-Read vs Long-Read mtDNA Sequencing: Which Is Better for Forensic Casework?A 2026 pedigree-based study comparing short- and long-read mitochondrial genome sequencing found no single winner: long reads improved…Read article Hair Examination in Forensic Science: Microscopy, DNA Analysis and Evidential LimitationsLearn forensic hair examination from collection and comparison microscopy to nuclear and mitochondrial DNA, including interpretation limits, case…Read article