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Archiver > GENEALOGY-DNA > 2006-04 > 1146307640


From: "John McEwan" <>
Subject: R1b SNP page updated
Date: Sat, 29 Apr 2006 22:47:20 +1200


Dear List

The R1b SNP page has been updated. There are 9 new changes.

See www.geocities.com/mcewanjc/s21.htm
www.geocities.com/mcewanjc/r1bsnp.htm

The major change has been 2 new M222 positive or derived entries, one is
an entirely new entry and one an existing entry that tested positive for
M222.

All have been previously classified as R1bSTR19Irish cluster (aka North
West Irish).

Now M222+ individuals and their origin and its (re)discovery process has
been well debated on this list. However, in my opinion we need quite a
few more test results before we can really get to grips with it. On
comparison, the 5 existing M222+ differ from each other by up to 11
marker mismatches. Gaylean is especially divergent from the other M222+
individuals and a DYS390=24 to boot. All have markedly closer matches to
R1bSTR19Irish modal than any other group. On clustering, all group
together and distinct from all the M222 negative individuals, who have
either tested M222 directly, or who can be inferred by being S21+ or
SRY2627+ or S28+.

The North West Irish cluster as defined using STRs has about 46% of the
diversity (ASD=0.197) of R1b (ASD=0.432) so it is quite old. The 5 M222+
individuals sampled to date have an ASD of 0.165 so while diverse it is
clear that the whole group has not yet been comprehensively sampled. The
modal of the 5 M222+ is almost identical to the North West Irish group
as a whole differing only slightly on CDYa and b.

One of the latest to test M222 positive is Decatur Blanchard. He traces
his roots back to England and has no Irish connection, even though his
STR haplotype is consistent with being M222+. The Blanchard name
clusters around Lincolnshire. While Decatur suggests it could just be an
erratic due to some Irish traveller it does hint at interesting
underlying questions: are there M222+ out there that do not have the
classic North West Irish STR profile and where are they located, or
conversely are there people who have the North West Irish STR profile
who are not M222 positive? Answering this question will provide very
useful information to both genealogists and those interested in deep
ancestry.

M269+ P25-
**************
Finally a little bit on M269+ P25- individuals. Today I was rereading
the paper on P25 reversions (Adams 2006, The case of the unreliable SNP.
Recurrent back-mutation of Y-chromosomal marker P25 through gene
conversion. Forensic Science International 159:14-20) and noted some
facts that I had previously overlooked. They tested 1000 males from the
Iberian peninsula and found 10 M173(xSRY1532b) P25- individuals (1%) and
22 out of 421 in the British sample (5.2%). Of these 31/32 were M269+
and one was also SRY2627+ (in the paper given as M167+).

My R1b SNP list in has 2 P25- out of 92 P25 tests that are otherwise
consistent with being R1b (2.2%) and this estimate is in a mid range
estimate of the above 2 populations. The combined results show that
there has been at least TWO reversions one in SRY2627+, and one in S21+.
What is not clear is what number, if any, have been within
R1b1c(xSRY2627,S21). The Adams paper Y STR network diagram based on 19
STRs provides only equivocal evidence of multiple founding events and
the variability observed of the reversions was similar to R1b as a
whole.

I say this, because I suspect the significantly higher level in the
"Great Britain" sample may be because of the percentage of S21 positives
in this population.

It has been estimated that gene conversion events occur much more
frequently than SNPs, but perhaps at a 10X lower rate than STR
mutations. If so the number of reversion events may be modest and some
lineages could be of reasonable size. The new EA SNPs may be able to
resolve this issue and identify at least some of the founding events.

The r1b SNP list also has a result Denney RS4EF, which has not yet been
tested for S21. Such a test would confirm at least a third reversion
event if it was S21-. I would certainly recommend that any individual
who is M269+ P25- to also tests for at least S21, S28 and SRY2627. The
outcome could be quite a reasonable diagnostic family SNP(s) especially
when also paired with STR markers.

As usual if you note any errors or omissions please contact me and also
if you have new data.

Cheers

John McEwan



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