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Archiver > GENEALOGY-DNA > 2005-07 > 1120234846


From: Robert Davenport <>
Subject: Re: [DNA] Back Mutation and Parallel Mutation
Date: Fri, 01 Jul 2005 09:20:46 -0700
References: <111.4d4beaa3.2ff6c3f2@aol.com>
In-Reply-To: <111.4d4beaa3.2ff6c3f2@aol.com>


We have exactly the same problem in the Davenport project, on DYS 576.

We either have a back mutation, or we have a parallel mutation.

Some descendants have a value of 19, and some have a value of 20.

We have two different immigrant Davenports, each of which had either 19 or
20 as a value for DYS 576 when they immigrated back in the 1600s.

If the original immigrants had a value of 20, then some of their
descendants have mutated BACK to the original marker of 19.

If the two immigrants each started with a 19, then independently, each has
descendants who have mutated to 20, give us the paralell.

So, I would also like to hear more about this.

It is ironic that we have exactly the same situation, with two different
immigrants.

One school of thought thinks that the immigrants both arrived with 19, and
we had paralell mutations to 20.

Another school of thought thinks that both immigrants arrived with 20, and
that we had independent back mutation to 19, on both lines.

So I guess I am suggesting a third category, which is INDEPENDENT BACK
MUTATION, i.e. when two different lines mutate back to an original marker,
independent of each other.

Thanks!







At 09:06 AM 7/1/2005, you wrote:
>Can one of you please define each of the above terms. As a layman, this is
>my understanding:
>
>Back Mutation: When it can be well documented with a paper trail that a
>particular individual has had a mutation from his father. This mutation is
>carried for a few generations, and then his descendent mutates back to the
>ORIGINAL value on the marker.
>
>Parallel Mutation: When it can be well documented with a paper trail that
>two branches of the same family have individuals who mutate, independently,
>and far distant from each other in geographic locality, to the same value on
>the same marker. In our family the mutation has occurred on DYS 437,
>probably
>from a 16 to a 17, but possibly from a 17 to a 16.
>
>On DYS 437 we have 12 persons who are a 16, compared to seven who are 17. We
>have studied in detail two of the seven families who are a 17, and noticed
>the common mutation from their immediate family, who are a 16.
>
>Please critique my understanding. Thanks!
>
>Mary Fern
>
>
>
>
>==============================
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