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Archiver > GENEALOGY-DNA > 2004-12 > 1104343872


From: David Wilson <>
Subject: Re: [DNA] 385a,b Upheaval in R1b (WAS: Can 385a,b = 14,15 be15/14?)
Date: Wed, 29 Dec 2004 10:11:12 -0800 (GMT-08:00)


I mostly agree with Ann's comment that marker uncertainty in multi-copy loci is probably not of great importance in genealogical time. But the distinction can be crucial when you are trying to make fine distinctions among individuals who share a common ancestor some 10-12 generations back, but whose intervening lines of descent are not clearly established.

Say you have a reservoir of tests which show 38,38 at CDYa,b as the modal or ancestral values for a family. Say you have two individuals whose results show 37,38 for this marker. Which copy changed? If the same copy changed in both, you have evidence of a more recent common ancestor for the two of them than for the whole group. If it could be shown that the mutation occurred in one copy in one person and the other copy in the other, you cannot demonstrate a more recent common ancestor for the pair than for the entire group.

This problem ALMOST crops up in the Lovelace/Loveless surname study, but because duplicate values at CDY a,b are the end state rather than the initial state, we know that the original lower value, regardless of its actual location on the chromosome, must be the one that mutated in each case.

Obviously with 464 the problem is more complicated than with markers in which only two copies are found.

David Wilson


-----Original Message-----
From:
Sent: Dec 29, 2004 8:47 AM
To:
Subject: Re: [DNA] 385a,b Upheaval in R1b (WAS: Can 385a,b = 14,15 be 15/14?)

First let me hasten to see that the problems with multi-copy markers are not
of great concern for projects dealing with the genealogical time frame. If you
have a cluster of people who match on most markers, you don't really need to
worry about whether some of them are really DYS385a/b 11,14 while others are
really 14,11.

<<snip>>



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