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African American DNA Research Forum

Re: Meaning of small letter added to haplogroup

From the FamilyTreeDNA website:

"Understanding Haplogroups...

The Haplogroup database tells you about your deep ancestral origins. One way to think about Haplogroups is that a Haplogroup is a branch on the tree of Homo Sapiens Sapiens and a Haplotype represents the leaves of the tree. All the Haplotypes that belong to a Haplogroup are leaves on the same branch.

The Y Chromosome DNA test is a STR test, also known as Short Tandem Repeats. A SNP test of the Y Chromosome, which tests deep ancestral Markers, determines the Haplogroup. The Haplogroup database consists of the test results of participants in studies conducted and tested by Dr. Hammer at the University of Arizona. These participants had either a 12 Marker or 25 Marker Y Chromosome STR test, and a SNP test. Therefore, a search of the Haplogroup database looks for matches of your Y Chromosome STR test results, and predicts your Haplogroup based on the Haplogroup of the participants you match. A SNP test can be ordered to confirm your Haplogroup.

The results from a search of the Haplogroup database not only provide information about your deep ancestral history, but the outcome can also be used to analyze Y Chromosome results.

The SNP test is available, and will only confirm or deny the estimated Haplogroup. If it ever occurs that the Haplogroup is not confirmed, a participant should contact Family Tree DNA for a consultation regarding further testing to determine the Haplogroup.

There have seen at least seven (7) systems in use in the scientific community for defining and naming Haplogroups. These various systems, which assigned different names to Haplogroups, often led to confusion. Depending on which system was utilized in the literature you read, Haplogroups had different names and definitions. To solve this problem, the Y Chromosome Consortium developed a new system to name Haplogroups and subgroups.

The new naming system developed by the Y Chromosome Consortium was designed to easily accommodate expansion, as new Haplogroups are discovered. This new system identifies and names the current known Y Haplogroups that have been discovered.

A Haplogroup is defined as all the male descendants of the single person who first showed a SNP mutation. A SNP mutation identifies a group who had a common ancestor far back in time, since SNP's rarely mutate. Each member of a Haplogroup would have the same SNP mutation as the common ancestor. These mutations are extremely rare, and identify a group of people over a period of tens of thousands of years.

The Y Chromosome Consortium has defined 18 major Haplogroups, called A through R, using capital letters. Each of these major Haplogroups, which are also called clades, can have subgroups, which are called subclades. The 18 major groups at the top level, A through R, represent the major divisions of human diversity based on SNPs on the Y chromosome.

Subgroups have a numeric name, which follows the Haplogroup name. For example, Haplogroup E has 3 subgroups, called E1, E2, and E3. There is also a subgroup E*, which are those that belong to Haplogroup E, but do not belong to one of the 3 defined subgroups, E1, E2, or E3.

If a subgroup has subgroups, they would be labeled with a lower case alphabetic character, such as E3a or E3b.

The new Haplogroup database at utilizes this new naming system developed by the Y Chromosome Consortium. On your search results page for Haplogroup, you will see the Haplogroup of those who match or are a close match to your Y chromosome test result. Depending on your Haplogroup search results, you will see Haplogroups such as I, J2, I1b, R1b. All Family Tree DNA explanations and terminology will utilize the emerging standard defined in the Y Chromosome Consortium paper.

The Y Chromosome Consortium scientific paper, which describes the Haplogroup naming system, can be found at the link below:

YCC Nomenclature System"

Art Thomas

18 Dec 2002 :: 14 Nov 2008
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