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mtDNA Haplogroup Origins Frequently Asked Questions

What are mitochondrial DNA (mtDNA) haplogroups?

Mitochondrial DNA (mtDNA) haplogroups are the major branches in our common maternal lineage. Your haplogroup traces your branch on the maternal tree of humanity back to our shared ancestor in Africa.

Are mtDNA haplogroups the same as Y-DNA haplogroups?

No, the names in the mitochondrial DNA (mtDNA) haplogroups do not correspond with the same names in the Y-chromosome DNA (Y-DNA) haplogroups.

How are mtDNA haplogroups named?

In general, scientists name mtDNA haplogroups according to their major branch with a capital letter. They then name subclades (branches) with alternating numbers and letters: H, H1, H1a, H1a1, etc.

  • H
    • H1
      • H1a
        • H1a1

Are there exceptions to the alphanumeric naming of mtDNA haplogroups?

Yes. There are two exceptions to the alphanumeric naming of mtDNA haplogroups. 

Zeros (0s) in the mtDNA Haplogroup Name

  • Zeros are used when a new branch point needs to be inserted above a well-established branch point on the mitochondrial tree. One of the best-known examples of this is the insertion of R0 between the R and HV branches.
    • R
      • R0 <–
        • HV

Note: In some older papers, the “pre” prefix is used instead of a zero. Thus, R0 was might be called pre-HV in these papers.

Apostrophes in the mtDNA Haplogroup Name 

  • Apostrophes are used to create a common branch between two well-established branch points in the tree. One example is M1’20’51. It is the common parent of the M1, M20, and M51 branches.
    • M1’20’51
      • M1
      • M20
      • M51

Note: Some branches of the tree that were joined before the apostrophe was adopted are joined without the use of an apostrophe by historic convention. Examples are HV, which was, when named, the parent of the H and V branches, and JT that is the parent of the J and the T branches.



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