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Archiver > DNA-R1B1C7 > 2007-07 > 1184989145


From: "David Wilson" <>
Subject: Re: [DNA-R1B1C7] Advanced Test for Northwest Irish
Date: Fri, 20 Jul 2007 20:39:05 -0700
References: <072020071128.13222.46A09C670004C74F000033A622058861729C029D9A0D01040D0E9F@comcast.net>
In-Reply-To: <072020071128.13222.46A09C670004C74F000033A622058861729C029D9A0D01040D0E9F@comcast.net>


Yes, I had the 464X test some time ago and show the same pattern Paul does:
ccgc. Most if not all R1b1c7 individuals are likely to have the same 3c/1g
pattern, though the order of appearance might differ based on the numerical
value of the g-allele.

Perhaps a word of explanation is in order for those who don't know what this
464 "X" test is all about. About three years ago, when there was very little
established differentiation among R1b1c haplotypes except what could be
suggested through STR clusters, Thomas Krahn discovered that it was possible
to make a slight distinction among the copies of DYS464. If you looked not
just at the number of repeats per copy but also inspected the flanking
regions of each copy, it was possible to classify the copies based on
whether there was a c or g in a particular location in a flanking region.
These differentiated copies of 464 then became known as c-alleles and
g-alleles respectively. What was interesting is that in most haplogroups,
464 was represented by four g-alleles. In R1b1c, however, there was
overwhelming representation of the 3-c/1-g pattern, and the g-allele was
almost always the copy with the greatest or next to greatest number of
repeats. In other words, the g-allele would almost always be associated with
464c or 464d, and the symbolic representation of this fact would be either
ccgc or cccg.

Rarely one would find an R1b1c haplotype with four c-alleles (or was it four
g-alleles?) or two c-alleles and two g-alleles. Given the apparent stability
of the c-type/g-type allele distinction at 464, these variants offered the
chance of functioning as "pseudo-SNPs," to borrow a phrase. In the absence
of the now-known major SNPs that let us subdivide R1b1c (including M222 for
R1b1c7), the use of X-testing for DYS464 offered the possibility of
quarrying out small clusters within the large M269+ population.

It is theoretically possible to use this X-testing to hunt for possible
subgroups within subclades, but it seems to me not worth the expense within
a small subclade like R1b1c7. Yes, an interesting 464X pattern can be used a
clustering marker and possibly even a family or clan marker if the change
occurred recently enough. But these changes are not common might not even
exist in a small haplogroup like R1b1c7.

It remains the case that RecLoH events (recombinatorial loss of
heterozygosity) can create mixes of c and g types when one of the copies of
464 is used as a wholesale replacement for another copy in the DNA copying
process. Thus an unusual 464X pattern could be found in individuals from two
different haplogroups. But that does not make them more closely related. The
SNP is still the most powerful organizational mutation.

I will never tell anyone NOT to order a test they really want, but I would
never encourage anyone to order the 464X test in the expectation that it
would be of use for close-in genealogical work.

David Wilson









-----Original Message-----
From:
[mailto:] On Behalf Of
Sent: Friday, July 20, 2007 4:29 AM
To:
Subject: [DNA-R1B1C7] Advanced Test for Northwest Irish

Although John McEwan is waiting for additional evidence, preliminary
tests of 464x for people of possible Leinster ancestry seem to show that a
test result of ccgg may well be an indicator.
Those of us who are R1b1c7 may not need additional proof, but it would be
interesting to determine whether 464x test results can be used for other
geographic origins. Have any other of you R1b1c7s been tested for 464x, and
if so, would you share your results? I tested as ccgc.
Paul Burns

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