The mtDNA Haplogroup X Project was opened in May, 2006 as a resource for those wishing to learn more about their Haplogroup.
This project is open to all assigned to Haplogroup X by their mtDNA test results.
Haplogroup X diverged from Haplogroup N more than 30,000ybp. It further split more than 20,000ybp into 2 main subgroups, X1 and X2. Haplogroup X is found in Europe, the Near East, Central Asia, North Africa and North America, and is believed to have migrated to the Americas about 15,000 years ago, making up a very small component of the Native American population (less than 3%). Bryan Sykes in his book named this mtDNA haplogroup Xenia.
Haplogroup X subclade X1 appears to be largely restricted to North Africa, East Africa and the Near East. It is characterized by an HVR2 mutation at 146. Haplogroup X1 is further divided into X1a and X1b.
Subclade X2 is more widely distributed throughout Mediterranean Europe, the Caucasus, the Near East and North America. Haplogroup X2 is divided into further subgroups. X2a is found in a few geographically diverse Native American populations, such as Navajo, Yakima and Ojibwa. It is characterized by a HVR mutations at 200 and 16213. Recent work has identified 2 sub branches of X2a. X2a1 in the Great Lakes area, and X2a2 in the west. Another Native American subgroup X2g has been identified as separate from X2a. X2b is the most geographically diverse, covering Europe and the Near East. It is characterized by an HVR2 mutation at 226. Recently an X2b1 subclade has been identified in a group of Moroccans. X2c is characterized by an HVR1 mutation at 255. X2d and X2e are characterized by mutations in the coding region that can not be differentiated from other X2's without additional mtDNA testing beyond HVR1 and HVR2. X2f is characterized by a HVR2 mutation at 257.
The lastest tree I use can be found at https://www.yfull.com/mtree/X/ which is based on https://phylotree.org/tree/X.htm. We are all anxiously awaiting the results of the Million Mito project
One theory of how the X Haplogroup ended up in North America is they migrated from central Asia along with the A,B,C, and D Haplogroups. It is interesting that no Haplogroup X traces have been found in Siberia. The nearest X Haplotypes have been found is the Altai region of central Asia. This theory is supported by yDNA studies [Zegura.]
Schurr postulates that Haplogroup X arrived in North America via the central corridor which became free of ice about 12500 ybp.
Another theory, The Solutrean Hypothesis, is that the there was a early pre-Clovis Atlantic migration route in addition to the Asian Bering Straight land bridge as shown on the following map:
Other more imaginitive theories include:
The Mormon hypothesis, which states the Haplogroup X in North American could be the result of descendants of Lehi and Sariah as mentioned in the Book of Mormon.
The Neanderthal Hypothesis. That Haplogroup X mtDNA is descended from the Homo Sapiens Neanderthalis. While there are some X motif markers present in some Neanderthal mtDNA samples, there are also many more differences.
And finally, the Atlantis hypothesis, Where Haplogroup X is identified with the remenants of the Atlantean civilization.
Other X mtDNA HaploGroup Web sites: WorldFamilies.net/mtdna/x