Mitochondrial DNA (mtDNA) Haplotype
Definition
A characteristic sequence of the mitochondrial genome used to assign an individual to a maternal lineage. More copies per cell than nuclear DNA, so it survives degradation better. Useful for victim identification from insects when nuclear STR yield is too low.
- Inheritance
- Maternal lineage
- Copy number
- Much higher per cell than nuclear DNA
- Advantage
- Survives degradation better than nuclear DNA
- Forensic use
- Identification when nuclear STR yield is too low
Common questions
Why is mtDNA especially useful for identification from insect-derived samples?+
Gut content or bloodmeal samples recovered from insects often contain very little intact human nuclear DNA, but because each cell carries many mitochondrial copies, mtDNA is more likely to remain amplifiable, giving investigators a usable lineage marker when nuclear STR typing fails.
What is the main limitation of mtDNA haplotypes compared to nuclear STR profiles for identification?+
MtDNA is inherited unchanged along the maternal line, so it cannot distinguish between maternal relatives, a mother, siblings, and maternal cousins can share the same haplotype, making mtDNA far less individualising than a nuclear STR profile.
Can an mtDNA haplotype match alone establish identity to the exclusion of all others?+
No. A match indicates the individual belongs to the same maternal lineage as the reference, which narrows but does not uniquely identify a person, so mtDNA results are typically used to include or exclude a maternal line rather than to individualise on their own.
Related terms
- Blood Meal
- Blood ingested by a haematophagous insect during feeding on a vertebrate host. The host's DNA persists in the insect's gut for hours...
- COI Barcoding
- DNA-based species identification using a standard 658 bp segment of the mitochondrial cytochrome oxidase subunit I gene. Sequences are matched against reference...
- Gut Content Extraction
- Physical dissection of a larva to remove the crop and midgut contents, which are then extracted separately from the larval carcass. The...
- Haematophagous Insect
- An insect that feeds on the blood of a vertebrate host. Examples include mosquitoes (Culicidae), sand flies (Phlebotomus, Lutzomyia), and certain midges...
- Mixed-Source Profile
- A DNA profile resulting from a mixture of two or more contributors. Gut content extractions routinely produce mixtures of insect DNA and...