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Archiver > GENEALOGY-DNA > 2008-02 > 1202497005


From:
Subject: Re: [DNA] When is SNP Testing Useful for Genealogists?
Date: Fri, 8 Feb 2008 13:56:45 EST



In a message dated 2/8/2008 11:37:27 A.M. Central Standard Time,
writes:

Close matches on the SG-43 should be sufficient, although there is always a
slight chance that a high-resolution match will break down on further
testing.


I have one I1a group of WEBBs for whom the SG 43 would not have been
sufficient. This family line is known to be from a man born in 1694 who had 6 or 7
sons (can never remember), most of whom had at least that many. This family
pretty much spread throughout the US from 1810- 1880 The 7 or so testees in
the group are about half "we know which line we came from" and half "wow we
didn't even know we belonged to this family!"

At 37 markers, they had a few scattered, isolated mutations among them --
only 2 of which matched and those two were CDYb mutation. While DNA-FP was
still an independent concern, we ordered from them the markers that are the
"difference" from the 32 the FTDNA37 and SG43 have in common and the SG43. Not a
single mutation in the bunch! We also ordered some of the DYF markers, and
it was there we found the first suggestions of a possible lineage identifying
mutation. Now I'm trying to sell them all on getting the 399 X upgrade
because this marker looks very much like it will determine at least two different
branch points.

FACT: You can never know when a given # of markers is "enough" because
mutations don't conveniently occur in the marker set offered by this company or
that company. You HAVE to look at the situation and be willing to test it
beyond a set number of markers if the situation requires it for the purposes you
have.

MY OPINION: A 37 or 43 or even 67 marker set which shows no variation at
all, or a few mutations but no patterns of matching mutations IS NOT ENOUGH if
you have a large group of matching people who don't know how they fit
together. How cheated I would personally feel if I belonged to a surname group in a
large group of people with x/x or x-1/x matches and had been told "x markers
is plenty" for years and then suddenly a new Admin said "let's go to x+y
markers and see what we get" and then, when we did, VOILA there was the pattern
of sub-branching we had been looking to find. As an Administrator, I make
the best efforts to get the most for the money, to avoid unnecessary testing,
but also to explore where we can to see what we can find out that we didn't
know before. When folks cannot afford it, I ask "Are you willing if I can find
the money to pay for it?" Sometimes it's my own money, sometimes I find
another person or a group of people who understand the goals of "seeing what
we can see."

I suppose my ancestors could have said "this little patch of land is enough"
and stayed in the UK, or "this life is enough" and kept driving a beer wagon
in Sölvesborg, but they didn't. Funny, we all seem to understand financial
ambition, or social ambitions, but intellectual ambition seems harder for some
of us to understand or adopt in some situations. I guess I have always
found it impossible to say "this much knowledge is enough" no matter what the
topic.



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