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A haplogroup is a genetic population group of people who share a common ancestor on the patrilineal or matrilineal line. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations.


Y chromosome DNA haplogroups

Y chromosome DNA (Y-DNA) haplogroups are determined by single-nucleotide polymorphism (SNP) tests. SNPs are locations on the DNA where one nucleotide has "mutated" or "switched" to a different nucleotide.

Because a haplogroup consists of similar haplotypes, it is possible to predict a haplogroup from the haplotype. A SNP test is required to confirm the haplogroup prediction. Not all the testing companies offer SNP testing, and consequently their customers' haplogroup predictions are sometimes inaccurate.

ISOGG maintains the most up-to-date version of the Y-SNP tree. The tree is updated as and when new branch-defining SNPs are discovered. The criteria for inclusion of SNPs in the tree are published here.

Phylotree maintains a minimal reference phylogeny for the human Y chromosome, an abbreviated version of the Y-tree showing only the principal branches. The Phylotree Y tree can be found here. Background information on the methodology of the tree and the SNPs included can be found here.

There are a number of tools that can be used to predict the Y-DNA haplogroup. For a full list see the ISOGG Wiki page Y-DNA tools.

Y-DNA haplogroup resources

See also

Mitochdondrial DNA haplogroups

When you have taken a mitochondrial DNA (mtDNA) test most companies will give you a prediction of your mtDNA haplogroup. The haplogroup can however only be confirmed by testing specific branch-defining single-nucleotide polymorphisms (SNPs), some of which are only found in the coding region. If no SNP tests are done there is a possibility that the prediction will be incorrect. mtDNA tests from Family Tree DNA (HVR1 and HVR2) and the Genographic Project version 1 (HVR1) include a panel of 22 SNPs to confirm the base haplogroup, but rarely can determine the specific subclade. Similarly, 23andMe tests a set of SNPs that predict haplogroup assigments according to a now-outdated version of the mtDNA tree. Therefore, for those who wish to discover or confirm their exact haplogroup (subclade) assignment and to know exactly where they fit on the latest version of the mtDNA tree (applicable to all future versions of the tree), they will need the mtFull-Sequence test (available from FTDNA) either for themselves or a relative in the their direct maternal line.

The most up-to-date version of the mtDNA tree is maintained by Mannis van Oven on the Phylotree website.

To check or predict a haplogroup assignment use James Lick's free mtHap tool. For additional mtDNA resources see the article on mtDNA tools.

mtDNA haplogroup resources

See also

General resources