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Archiver > GENEALOGY-DNA > 2005-01 > 1105668796
From: "Terry Barton" <>
Subject: RE: [DNA] Male Line Specific Y-STR Average Mutation Rates -- the one size shoe/(haplotype mutation rate) fits all approach is not valid, imo -- corrected URL link
Date: Thu, 13 Jan 2005 21:13:25 -0500
In-Reply-To: <REME20050112202951@alum.mit.edu>
John, our Barton family has 65 + men in our R1b Lineage I. This is bound to
be one of the largest surname groups in a single genetic lineage. We have
relatively few mutations, with a "calculated" (required some assumptions)
mutation rate of .0016 a while back - using the original RG 26 marker
results.
My original calculation used the same logic of mutation opportunities and
actual mutations as the recent discussions (counting as one mutation the
shared result of several men and only those generations of mutation
opportunity). The estimate comes from the fact that I had to make an
assumption of how many generations were missing where the paper trails don't
connect. (I have some 25 separate families in this group of men - as
defined by earliest known ancestor). If one assumes a nominally quick
merging of the 25 families into one family, at 26 markers, one gets the
.0016 mutation rate. If the common ancestor(s) lived longer ago than I
assumed, then the calculated mutation rate has to go down further due to
more mutation opportunities.
I haven't had time to redo my calculation with the current focus on mutation
rate by panel and have the further confusion of having nearly all my men
tested by RG at 26 markers, plus 20 odd tested at FTDNA 37. I have another
18 men in test right now - half at 37 markers and half upgrades from RG26 to
FTDNA37 (yields 42), plus a few tested at RG 43. As a result, I have men at
26, 35, 37, 42, 43 & 48 markers and have an ancestral halpotype for 47 of
the 48 markers. (I don't know which was the mutation at CDYb, but there is
a single 17th century mutation there to count) I am inclined to wait for my
info to stabilize before doing a new calculation. (Plus I will have to
recreate some info lost in the worm destruction of our website)
My comment is that adding another 65 men (and doubling my data set) would
almost certainly not move our mutation rate significantly toward "the
average rate". Consistently, we see 0, 1 or 2 mutations in each test
participant against the ancestral haplotype. I'd have to suddenly get twice
as many mutations in each of the next 65 men (as we have been seeing) to
bring us up to an "average" rate.
My belief is that some families have noticeably lower or higher mutation
rates than the average - while still falling into the expected overall range
of mutation rates. We are one of those. We don't know why. We just see it
as our situation - and I really don't think that further testing will bring
our observed mutation rate up to "average".
A while back, I calculated that this group of men were tested on an average
of 31 markers. When I get the 18 results back, the average will be closer
to 35 or 36. How many men with 35 (or 37) markers, with each contributing
an average of 5 generations of mutation possibility would it take to have a
"statistically valid sample"?
Terry
-----Original Message-----
From: John Chandler [mailto:]
So far, I have not heard of *any* family with a rate that was
*significantly* higher or lower than average. *All* of the reports of
really extreme mutation rates have come from modest-sized projects
with correspondingly large uncertainties. Larger projects come closer
to the average (as expected).
John Chandler
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