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Old 8th January 2009, 12:01 AM
DKF DKF is offline
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Join Date: Oct 2007
Location: SoCal
Posts: 263
X chromosome ancestry testing: Selecting the right candidate

I posted this to Rootsweb, but it occurs that some here might also be interested in exploring the information written on the X chromosome.

After tapping out Y-DNA and mtDNA testing, and learning more or less all (to
this point) that the information can tell me (until the dating "issue" is
better resolved), it seems that shifting gears toward autosomal and X
chromosome testing is the logical alternative.

After spending a great deal of time documenting Native American ancestors
the question is whether DNA testing of any sort can assist. Since the paper
trail is so detailed, why bother? In two words, "cross validation".

Unfortunately the mtDNA line dead ended before 1900. The YDNA lineage poses
problems in finding a suitable candidate that can be securely linked to
either he Hill or Green lines. At some point testing of candidates at
Tyendinaga, Ontario may be undertaken since in this location all
individuals of these surnames are presumably descendants (assuming no
unrecorded adoptions and npes).

Testing of myself and various relatives with autosomal DNA via DNAPrint and
DNATribes has provided data for consideration, but the results of testing
with the former test have provided small percentages of either Native
American or East Asian. Still, this seems rather non-specfic, and the
concerns surrounding the validity of the data yields unsatisfactory
findings. All of this rather pales in comparison with the one milltion to a
half million markers available via the new chip technology. The question
is, can this new technology overcome the obstacles noted above?

Fortunately, in terms of minority ancestry testing, there is good news and
bad news. The good news is that our family has a wide variety documentary
sources pertaining to our Six Nations ancestors going back from a birth in
1747, five generations into the 1600s. The bad news is that for me, that
means that this ancestor has made a .004% (1/256) contribution to my
genome. Hence there is unlikely to be more than a "trace" of this
non-European lineage. There are family members who, due to being the
youngest child of the youngest child, are 5 generations removed from the NA
ancestor, whereas I am 8 generations. Hence there would be a 1/64 or 2%
genomic contribution. There is every possibility that this would be more
substantial due to the vagaries of recombination at each meiosis, or could
in fact be zero or undetectible. The Finonacci series to the rescue.

The X inheritance is like nothing else in genetics. For example, of 128
ancestors at the 7th generation, only 21 have the opportunity to make any
sort of contribution. For example, if you are a male, your father made a
zero contribution since you obtained your Y from him, and your X from your
mother. The mtDNA ancestor will make a 1/64 contribution at the 7th
generation and the mother's father's mother's father's mother's father's
mother will make a 1/8 contribution. By some quirk of fate this woman at
the top of the fan chart created by Blaine Bettinger:


is my Native American ancestor. The upshot is that despite my low (under
the radar) autosomal link to this woman, she made a 1/16 contribution to my
X genome. What is interesting is that my mother's brothers (one remains)
have a 1/8 contribution. I always thought that the zig zag back and forth
between male and female gave me a lesser tie to my ancestor, but the
opposite is correct.

Thanks to Anders and the browser at decodeme, we have determined that the
largest block on my X which matches anyone in the 51 groups of the Human
Genome Diversity Panel (worldwide) is 364 SNPs (circa 5 Mb haploblock), with
a perfect match to a Xibo tribesman of Manchuria in northeast China, and the
only other close match is to a Yakut, and there is a secondary match to a
Yakut within this block. Manchuria (original home of the Xibo) and Lake
Baikal (original home of the Yakut) are considered to be the "home" of
Native Americans before the migration(s) beginning circa 15 KBP.

All of the high matches (6 or more "high matching" regions) are northern
East Asian (Xibo, Daur, Miao, She, Tujia), Native American (Pima, Suri),
West Asian (Hazara, Balochi), and European (Sardinian, Italian, Tuscan).
The Uyghur individual with 11 "high matching" regions is by far the closest
match on the X. This is odd, since there is no or low matches to all
northern Europeans (my primary background) except one person who is Colonial

Now the decision, to test my uncle, or not, since decodeme offers "more" in
relation to anything concerning the X chromosome (and the browser is
excellent). How much more information would this provide. As an "RP"
(retired person) I can no longer test anyone "just because".

Perhaps those of you considering what the X can or cannot tell you about
your ancestry might want to fill in the fan charts and see whose DNA is
likely to be represented on this chromosome. Recall though that, as Ander's
(Norwegian ancestry) match to a Mongol and Pima shows, interpretation is not
necessarily straightforward. At this point, being as objective as possible,
my Xibo and Yakut matches may be interesting distractors - only time will
tell. At some point individual European ancestors may be identified or
recognized by their signature on the X - I don't see this as in any way a
pipe dream - just something that awaits further developments.
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