The Bottom Line
A person is classified as belonging to Haplogroup W if they have a change to their mtdna compared to the Cambridge Reference Sequence at letters 1243, 3505, 8994, 11947, and 15884. In studies so far these five changes are unique to Haplogroup W. There are other mtdna changes that most or all W's share (see below). But these other changes are seen in other haplogroups and so do not unambiguously classify you as a W.
These changes do not involve the HVR1 and HVR2 regions (letters 16001 to 16569 and 1 to 574) that you probably had tested for genealogy purposes. However Family Tree DNA (FTDNA) conducts a separate test of 22 locations outside of HVR1 and HVR2 to assign customers to a haplogroup. FTDNA classifies you as a W if you are 1243C (the five other locations are not tested due to the expense). One of the 22 markers tested is 13263 (used to define haplogroup C). Coincidentally, this is also the change that defines haplogroup W subgroup W3a1. So if you have 13263G here, Family Tree DNA reports you as W3.
Members of the W haplogroup, compared to the Cambridge Reference Sequence, do have other common changes in their HVR1 and HVR2 mtdna. While these are not used to define W, they are common to nearly all W's. The complete list of common W haplogroup changes are:
- In HVR1 changes of 16223T, 16292T and 16519C.
- In HVR2 073G, 189G, 195C, 204C, 207A, 263G, 309.1C, and 315.1C.
Tests of the complete mtdna for over 100 persons have allowed subgroups (W1, W3, W4, W5, W6) to be identified, and sub-subgroups within those. The latest semi-official definition of these subgroups is at phylotree.org.
Network of All Full-Sequence Haplogroup W
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