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Archiver > GENEALOGY-DNA > 2002-09 > 1031670445
From:
Subject: Re: [DNA] HG1 and HG26
Date: Tue, 10 Sep 2002 11:07:25 EDT
In a message dated 09/08/02 11:28:11 AM Pacific Daylight Time,
writes:
> If I am reading the Table correctly, aren't the Rose results just as
> close to HG26 as they are to the HG1 haplotype? Why was HG1 selected
> instead of HG26? I do not know how to read the table population
> indicators, therefore, I cannot tell in what part of the world HG26 is
> most prevalent. Will someone help me understand the selection of HG1
> over HG26 and also shed some light on how to read the chart. Thanks.
Well, I am going to break my vow of silence on the topic of haplotypes and
haplogroups <g>. You may recall that I felt people were getting too hung up
on assigning their haplotypes to haplogroups. Remember that haplogroups are
defined by slowly changing markers, and population geneticists who deal with
global migration patterns over thousands of years like them for that reason.
Haplotypes use more rapidly changing markers, which are much more useful for
the genealogist. But I can't deny that many people find haplogroups a
fascinating topic.
Your haplotype using the 6 traditional markers DYS19, 388, 390, 391, 392, and
393 was 14-12-24-11-13-13. This does indeed correspond with what Wilson
called Haplogroup 1 or the Atlantic Modal Haplotype (AMH) in his paper, which
focused on Europe but also included some data on the Middle East.
http://www.pnas.org/cgi/reprint/98/9/5078.pdf
Now, the Nebel paper, which you studied so carefully, used samples
exclusively from the Middle East.
http://www.journals.uchicago.edu/cgi-bin/resolve?AJHG013033PDF
Each article has first defined the haplogroup for each sample, then performed
the haplotype tests. It's not surprising that different samples have
different modal haplotypes. This can be caused by "genetic drift" -- as some
people migrate and some people stay at home, the percentages of various
haplotypes in different populations will vary.
The exact AMH occurred 1 time in Nebel's Hg1 samples and 1 time in his HG26
samples. However, I think if you tally up all the close matches (including
some 5 out of 6 matches such as his haplotype pattern #17 with 10 cases),
that the AMH falls more comfortably into Hg1.
But this still brings up an interesting point -- the AMH did occur in two
different haplogroups. How could this be? If you look at Figure 1, you see
that Hg1 is an offshoot of Hg26. Now the person who had the mutation which
separated Hg1 and Hg26 had a specific haplotype. We can't know what that
haplotype was for sure, but it could very well be something close to the AMH.
100% of his descendants will inherit his haplotype and begin to accumulate
variations as the generations pass. But at the same time, he was not the only
person with his haplotype -- he would have had brothers or cousins who stayed
in Hg26. Their descendants will inherit the haplotype and continue to
accumulate variations, along a different random path.
The two samples of AMH in Hg1 and Hg26 thus could be "identical by descent"
(IBD) from a common ancestor who lived before the split between the
haplogroups. They could also be "identical by state" (IBS) -- that is, two
independent lines just happened to have added or deleted repeats at various
loci so they end up identical just by chance.
Since the studies are all based on just those six classical markers, it would
not be surprising to find some cases which are IBS. Since genealogical tests
use a much larger number of markers, it's less likely that people who have
the same haplotype actually belong to different haplogroups.
The abbreviations for the populations in Nebel's paper are at the very end of
the table, on p 1111.
So what are the take-home lessons here?
1) Every haplogroup has many haplotypes.
2) The modal haplotype may differ in different populations.
3) All of this work is based on just a few hundreds of samples.
4) Your haplotype (that is, the results of your Y-DNA tests on whatever
markers were used) is far more specific and genealogically informative than
your haplogroup.
Ann Turner
GENEALOGY-DNA List Administrator
http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html
DNA preservation kits: http://www.dnafiler.com
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