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From: "Ken Nordtvedt" <>
Subject: Re: [DNA] TMRCA calculation (was re: Felstead TMRCA, hg E3b)
Date: Thu, 22 Sep 2005 14:21:29 -0600
References: <380-220059220214337977@M2W087.mail2web.com> <43308839.6020402@dna-fingerprint.com> <REME20050920182157@alum.mit.edu> <op.sxfa9wsxpqnhvj@pablo> <009001c5be39$39effe50$0100a8c0@chrissam> <op.sxfdbclzpqnhvj@pablo> <00c101c5be3e$424f7300$0100a8c0@chrissam> <001c01c5beb5$a6d62fe0$0100a8c0@chrissam> <op.sxg1kudbpqnhvj@pablo> <003e01c5bf02$b79062e0$0100a8c0@chrissam> <op.sxg849xapqnhvj@pablo> <001801c5bfa2$3d101b00$0100a8c0@chrissam> <op.sxio70hnpqnhvj@pablo> <000a01c5bfa9$5e4beea0$71509045@Ken1> <op.sxirzmhnpqnhvj@pablo>


I should have been more verbally true to the TMRCA curve derivation myself.
The controlling rate for the curves is the sum of all the marker rates. The
testing companies like to express this sum of rates as the average rate
times the number of markers. Ken
----- Original Message -----
From: "David F Reynolds" <>
To: <>
Sent: Thursday, September 22, 2005 1:48 PM
Subject: [DNA] TMRCA calculation (was re: Felstead TMRCA, hg E3b)


> On Thu, 22 Sep 2005 12:11:00 -0700, Ken Nordtvedt <>
> wrote:
>
>> But the rate to be used in a TMRCA is the AVERAGE rate for all the
>> markers
>> present in the haplotypes being compared. The individual rate for the
>> marker or markers seen to have mutated are not to be singled out. The
>> only
>> thing that the individual rates is relevant to is how relatively often,
>> after lookking at many cases, you should see the different markers being
>> the
>> ones that have mutated. In other words, you should see more cases of the
>> fast markers having mutated than the slow ones.
>
> How does that reconcile with the statement below from Bruce Walsh, which I
> read to mean that a single mutation rate is used for convenience? (I'm not
> quibbling here, just trying to make sure I understand a complicated topic.
> :) --david
>
> http://nitro.biosci.arizona.edu/ftdna/models.html#Mutation
> It is likely that mutation rates differ at microsatellites. Again, if we
> could find those with the highest mutation rates, these will provide the
> most information. Since this information is still unresolved, for a first
> pass, we will assume all microsatellite markers have the same rate (as
> information on rate differences becomes available, the calculator will be
> updated to allow for marker-specific differences).
>
>
> ==============================
> Census images 1901, 1891, 1881 and 1871, plus so much more.
> Ancestry.com's United Kingdom & Ireland Collection. Learn more:
> http://www.ancestry.com/s13968/rd.ashx
>
>


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