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Archiver > GENEALOGY-DNA > 2007-07 > 1183322315


From: "Joe Knapp" <>
Subject: Re: [DNA] Human X chromosome: 5 main haplotypes
Date: Sun, 1 Jul 2007 16:38:35 -0400
References: <mailman.19816.1183089321.3678.genealogy-dna@rootsweb.com><20070629081643.TQYI20226.oaamta04ps.mx.bigpond.com@DINOSAUR><a81622ac0706290514t63a7a9f7y3610e98682248a91@mail.gmail.com><006d01c7bc02$e170a1c0$640fa8c0@Villandra2>
In-Reply-To: <006d01c7bc02$e170a1c0$640fa8c0@Villandra2>


On 7/1/07, Dora Smith <> wrote:
> So one set of markers came from my father, and the other from my mother.
> One of my father's markers necessarily came from his father. But did his
> father get the marker from his father or his mother? The advantage of Y
> DNA and mt DNA is that you can associate the findings with particular lines,
> so long ago you know where that line came from.

Maybe it would get more informative if a lot more supposedly
non-recombining X segments are found. What if a hundred such segments
could be identified? In that case there'd be a very high probability
of getting at least one from each g-g-grandparent.

The authors state in conclusion: "Other non-recombining regions in the
human genome, as they are identified, can likewise be explored for
phylogeographical studies, each one providing a fresh perspective on
human evolutionary history."

On whether the X segment identified is truly non-recombining, they
seem to not be equivocal, based on the linkage disequilibrium they
measured. But it's interesting that an earlier paper (Jan 2007) one of
the authors of the current paper studied another potentially
non-recombining segment that didn't pan out:

"No detectable linkage disequilibrium between the most external loci
DXS995 and DXS1050 was observed. Thus, even though recombination may
be absent on short time spans, as seen in the CEPH pedigrees, on a
long term basis it occurs often enough to dissipate all linkage
disequilibrium."

Joe

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