Haplogroup
Definition
A monophyletic branch of the human mitochondrial (or Y-chromosome) phylogenetic tree defined by a set of derived mutations. Haplogroup assignment is the first step in placing an mtDNA or Y-STR haplotype within the known landscape of human genetic diversity.
- Structure
- Monophyletic branch of the phylogenetic tree
- Marker basis
- Defined by shared derived mutations
- Applies to
- Mitochondrial DNA or Y-chromosome lineages
- Forensic role
- First step in placing a haplotype within known diversity
Common questions
How does a haplogroup differ from a haplotype in casework?+
A haplotype is the specific sequence of variants observed in one sample, while a haplogroup is the broader tree branch that haplotype belongs to, so haplogroup assignment situates a result within known global genetic structure before finer comparison.
Why does haplogroup assignment matter before comparing an mtDNA profile to a database?+
Confirming the correct haplogroup first flags obvious database mismatches or laboratory errors early, and checks that the observed variants are consistent with a biologically plausible lineage rather than an artifact.
Can haplogroup alone identify a specific individual?+
No, a haplogroup only narrows a sample to a broad population branch shared by many unrelated people, so it supports geographic or ancestry inference rather than individual identification on its own.
Related terms
- E-Value (BLAST)
- The expected number of alignments as good as the query result that would occur by chance in a database of the given...
- EMPOP SAM2
- The submission quality-assurance module used by the EMPOP database to screen incoming mtDNA sequences for phylogenetic inconsistencies, sequencing artefacts, and nomenclature errors....
- INSDC
- International Nucleotide Sequence Database Collaboration, the three-way partnership between GenBank (NCBI/NLM, US), ENA (EMBL-EBI, UK/EU), and DDBJ (National Institute of Genetics, Japan)...
- rCRS
- The revised Cambridge Reference Sequence (GenBank accession NC_012920), the standard reference for human mitochondrial DNA. All mtDNA variant positions in forensic and...