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Big Y - Lifetime Analysis

After your Big Y has been completed and as your or other users' results are upgraded or new variants are being considered for analysis, changes might happen to the tree to reflect the new evidence. This is a perpetual process for FamilyTreeDNA Big Y tests, meaning that you test once and get results for life (and your relatives can also benefit from it in the future).

New test results that can cause changes to the Haplotree, either by forming new subclades or refining existing subclades, are automatically detected and reviewed continuously. There is no guarantee that such a change will happen, or that it will happen within a certain time frame. 

Sometimes a new result will not contain any evidence that supports a change in the tree structure. This means that there will not be any changes to the haplotree until another tester from the same lineage upgrades. This is normal. Accuracy is the number one priority and our phylogenetic expert always strives to keep the tree as up-to-date as possible.

Our phylogenetic expert builds and expands the Haplotree from new and existing Big Y results. When new results are completed, you are able to view your positive, negative, and no-call SNP results. These will automatically place you on a specific branch in the Haplotree. You’ll also be provided a list of Private Variants, or SNPs that are previously undiscovered because they’re from an undertested part of the Haplotree, or because they are unique to your direct paternal lineage. 

FamilyTreeDNA’s internal tools let our phylogenetic expert view which new results and which existing results have opportunities to create new branches on the Haplotree or to split an existing branch. We’re able to view and compare those automatic calls for specific blocks: the positive, negative, and ones that were listed in your results as “no calls.” If a result was automatically a “no call” for you, we’re able to view if that was because it did not reach the coverage threshold to be automatically called and if there is enough evidence to make a different determination.

Through this process, the Haplotree has grown exponentially since the creation of the Big Y. Before the Big Y, a group called the Y Chromosome Consortium created a Haplotree in 2002 and maintained it until 2008. 

  • YCC tree 2002: 245 SNPs, 153 branches, only had discovered haplogroups A through R
  • YCC tree 2008: 599 SNPs, 311 branches, added branches C, F, S, T
  • YCC tree 2010 (final update): 440 branches
  • The Big Y was first available in 2014. 
  • May 2015 1st big Y: 6,556 SNPs
  • Nov 2016: 23, 767 SNPs
  • Nov 2017: 58, 590 SNPs
  • May 2018: 100,000 SNPs

In January 2019, we released the Big Y-700, which improves the technology behind the test and provides more coverage than the original Big Y and the Big Y-500. On average, Big Y-700 testers will receive 50% more SNP coverage than Big Y-500 or original Big Y testers, and about half of those additional coverage, SNPs will be able to be used as new branching points on the Haplotree. 

By the end of the first year after releasing the Big Y-700, the Haplotree had doubled in size. 

  • Dec 2019: 200,000 SNPs, 20,000 branches
  • December 2020: 350,000 SNPs, 35,000 branches
  • May 2021: 400,000 SNPs, 40,000 branches
  • December 2021: 50,000 branches
  • December 2023: 75,000 branches

If you are in an area of the Haplotree where there is still limited refinement and there are limited other Big Y testers, we strongly recommend reaching out to your Y STR matches and encouraging them to upgrade to the Big Y-700; more results in your section of the Haplotree may allow for changes to this part of the Haplotree, allowing you to learn more about when and where you share a common ancestor with your matches and the ancestral journey of your direct paternal line.

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