FamilyTreeDNA has released the brand-new Mitotree, version 2025.10.24!
Mitotree has sprouted 12,773 new branches, a 30% increase in size in just seven months!
Chart courtesy of FamilyTreeDNA, click to enlarge
The new Mitotree has a total of 53,856 branches utilizing 342,000 full sequence samples from multiple sources:
- 267,000 from FamilyTreeDNA full sequence tests
- 50,000 from GenBank and other third-party sequences
- 5,000 from the 1000 Genomes Project samples
- 2,000 from miscellaneous academic studies
Care was taken to curate studies and samples from rare and underrepresented populations.
When the Mitotree is updated, new branches aren’t just tacked onto the ends of branches like leaves. That’s because new samples may split existing branches far upstream of the tips of the branches, so the entire branch may have shifted or been divided into two.
Therefore, with each new Mitotree version, the entire tree is rerun, which means a new branching structure, and the possibility of a new or refined haplogroup for every customer.
Sample Evaluation
The samples tested at FamilyTreeDNA conform to stringent quality control measures, but quality control and alignment for samples originating in other facilities are unknown.
Samples from third-party academic sources are reviewed by the R&D team for potential issues before inclusion.
Ancient Samples
The November 2025 Mitotree now incorporates more than 10,000 ancient DNA samples from archaeological sites around the world.
These samples are displayed on the mtDNA Discover Time Tree, shown above, with brown lines and little trowels.
Additionally, you’ll find ancient samples displayed on the following Discover pages:
- Your individual Match Time Tree with your mitochondrial DNA matches when you click through to Discover from your account at FamilyTreeDNA
- Migration Map
- Ancient Connections
- Classic Tree
Mouse over the sample names to read about each one.
Ancient DNA (aDNA) samples are uniquely important, because they allow us to put a stake in the ground (pardon the pun) at a specific place and time when and where that individual lived.
Ancient samples also pose unique challenges due to their age and DNA degradation. The resulting sequence may be incomplete due to lower coverage. The sequence may also contain post-mortem damage artifacts caused by a process known as deamination. On the other hand, these artifacts can also be valuable in authenticating the ancient origin of the DNA, and that the sequence is not a result of contemporary contamination.
FamilyTreeDNA cannot resequence the ancient sample itself, so must rely on the results produced by the institution that processed the ancient DNA sample.
Fortunately, the FamilyTreeDNA R&D team has developed methodologies to compensate for these issues, identify which samples can be used to construct the tree, and which samples can be reliably placed on the tree. Only the highest-quality ancient samples can be fully included in the tree construction, meaning they are allowed to split and form new branches.
In this version, more than 2,000 ancient samples were utilized for the tree, which resulted in over 500 new branches that would otherwise not have formed. In future versions, more ancient samples will be evaluated and added.
There are now more ancient samples available for mitochondrial DNA than for the Y-DNA tree. Both males and females have mitochondrial DNA, but only males have a Y chromosome. There are more ancient samples in the queue to be added to the next Mitotree version.
Innovation
Mitochondrial DNA, by its very nature, includes challenges not present in either autosomal or Y-DNA.
Innovative tree-building methodologies have been devised and implemented, including new methods for handling complex scenarios where multiple variants conflict with each other. In some cases, mutations that exhibit unstable behavior in a certain part of the tree are ignored when analyzing that portion of the tree. This, and much more, will be detailed in a future white paper.
One size does not fit all, and the team has been very focused on identifying the best fit for a variety of scenarios. These methodologies and refinements have enabled the formation of more than 4,000 branches by using previously excluded private variants.
How the New Mitotree Affects You
Watch your email for a new haplogroup notification!
Further refinement of the Mitotree, either for you or your matches, can provide you with new genealogical clues.
A new haplogroup may regroup your matches to be more genealogically relevant, and your TMRCA (Time to Most Recent Common Ancestor) estimates may have been refined.
Everyone who received their mtDNA Full Sequence test result before October 24, 2025, but whose Mitotree haplogroup was still analyzing should receive their new haplogroup within the next few days.
Many customers who have already received their Mitotree haplogroup will also receive an updated haplogroup due to changes in the tree structure.
Customers who get a Mitotree haplogroup for the first time and customers who receive an updated Mitotree haplogroup should receive automatic email notifications.
The excitement isn’t restricted only to people with new haplogroups.
Everyone should check their haplogroup results on mtDNA Discover to see whether they match any of the newly included ancient DNA samples, if their haplogroup age has changed, or if their matches on the Match Time Tree have been regrouped.
You just never know what, or who, might be waiting for you!
Great Time to Upgrade
If you or a family member took one of the earlier, partial (HVRI or HVRII only) mitochondrial DNA tests, or you’ve received a haplogroup estimate from an autosomal test at another company, now, with the holiday sales, is the perfect time to upgrade an earlier test or order a new one.
A full sequence mitochondrial DNA test is required for your most refined haplogroup, your closest matches, including ancient DNA, and the Match Time Tree, at mtDNA Discover.
If you’re taken a mitochondrial DNA test, but are uncertain about which level, sign on to your FamilyTreeDNA account and check your dashboard.
If you’ve taken the full sequence test, both the Plus and Full squares will be pink. If the Full square is grey, click on it to upgrade.
You can’t benefit from all of these new advances without a full sequence test, and you’ll match other full sequence testers who share the same ancestor at some point in time.
Mitochondrial DNA has the potential, due to tracking the direct matrilineal line, to break through brick walls that no other test can touch!
Do you have a brick wall that needs to fall?
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Hi Roberta,
It is amazing to see so many new branches added after such a major update in February of this year. Many thanks to you and the rest of the team for all you have achieved – this will make a big difference to so many of us and I look forward to more testers bringing even more granularity to our matches in the coming months and years.
I ALSO FILLED OUT THE PERSONAL SURVEY FOR THE MATERNAL LINEAGE. I WAS SURPRISED TO SEE HOW FAR I ACTUALLY WENT BACK! WITH MYSELF = 0, I GO BACK 5 MORE GENERATIONS!
Hi. I looked at my mitrotree results. My mtDNA is u6a7a1b. Surprisingly, my sister is on a separate sub-branch of the u6a7a1b tree. We are one genetic distance from each other because I have a heterplasmy A215R that she doesn’t have. Also, some of my genetic distance 3 matches are now classified as u6a7a1f. Is that a new branch?
When I checked my variable coding mutations against the u6a7a1a group, my mutations were the same as theirs. However I do have C150T (Sephardic Jewish) and A215R (heteroplasmy) in HvR1 /2 group.