mtDNAtests

mtDNA tests analyze human mitochondrial DNA, the small circular genome found in mitochondria. Mitochondrial DNA is inherited almost exclusively from the mother, does not recombine, and is present in many copies per cell. These features make mtDNA useful for tracing matrilineal ancestry, studying population history, and analyzing degraded or ancient samples where nuclear DNA is limited.

There are two common testing approaches. One focuses on sequencing the hypervariable regions of the control region (often HVR1 and HVR2), which provides information about maternal lineage but with limited resolution. The other sequences the entire mitochondrial genome (the mitogenome), offering higher resolution and more reliable haplogroup assignment. Methods include Sanger sequencing and next-generation sequencing, with results compared to a reference sequence such as the revised Cambridge Reference Sequence (rCRS) or RSRS to identify variants and assign a haplogroup.

Applications span genealogical research, anthropology, and forensic science. In genealogy and population studies, mtDNA helps place a person on a matrilineal family tree and infer geographic origins. In forensics, mtDNA testing can be used when nuclear DNA is too degraded or scarce, such as in hair shafts or ancient remains, but it generally cannot distinguish between individuals who share the same maternal lineage.

Limitations and interpretation considerations are important. Because mtDNA is inherited from a single line, it cannot reveal paternal ancestry and cannot uniquely identify a person. Shared mtDNA among maternal relatives reduces individual discrimination. Heteroplasmy, contamination, and database dependence can complicate results. Ethical and privacy concerns apply, especially in consumer testing, and clinical mtDNA tests may screen for pathogenic mutations separate from genealogical analysis.