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Archiver > GENEALOGY-DNA > 2008-05 > 1211131045


From: Nelda Percival <>
Subject: Re: [DNA] Y-DNA tEsting- what constitutes "match".
Date: Sun, 18 May 2008 12:17:25 -0500
References: <c89.29fc87ee.3561a304@aol.com><003a01c8b908$25693d30$0100a8c0@john>
In-Reply-To: <003a01c8b908$25693d30$0100a8c0@john>


AJM,
I totally agree with you, thats why to me you test as many markers as you can get them to test.

A mismatch at 4 in 12 may still be a match at 67 markers in that is the only differences.

but, you have to set a standard until you start understanding the results. yes if (not an example.. ) you had DYS19= 36 then I'd look for a lab error and if I had two then it would be something I would bring to the table here on this list... odd results for a particular marker need more experienced help from you all!

n.Regards: Nelda Percival http://freepages.folklore.rootsweb.com/~bonsteinandgilpin/ > From: > To: > Date: Mon, 19 May 2008 04:56:38 +1200> Subject: Re: [DNA] Y-DNA tEsting- what constitutes "match".> > I sometimes feel that different people have different standards for judging> what "match at 12 markers" and "don't hold up at 25 markers" mean.> > I tend to think that a 12/12 match, where both are exactly AMH, for> practical purposes should not be treated as a significant match. On the> other hand, if two haplotypes have in common 2 or 3 unusual off modal marker> scores in the first 12 markers, I would be looking at 10/12 or even 9/12 as> having potential to be related. In one group I have two persons with 4> mutation steps difference at 12 markers, who matched on a distinctive family> marker, who in the context of the wider picture, I considered likely part of> the same family. At 37 markers when they were later obtained, bearing in> mind a range of distinctive family markers, they look well and truly related> to me.> > It is a bit simplistic to say 10/12 is or isn't a match, or 4 mutations> difference on 12 markers isn't a match, without looking at distinctive> family markers, and then looking at those two haplotypes in a wider context.> > At 6 mutation steps on 25 markers, there is realistic statistical> possibility of them being related since surnames. Are people saying that 6> mutations steps on 25 markers is a match "falling apart"? Perhaps it is> just a recLOH or some such event? Perhaps testing 67 markers would reveal> more? I think if at 25 markers, it can't be realistically discounted that> they are related since surnames, then it is premature to say it is not a> match, or the match has fallen apart.> > In one past situation, I had if I recall correctly only 2 markers> overlapping between different marker sets tested by different persons. One> of those markers was very unusual, and distinctive to a particular family.> On the basis of that 2/2 match, which included a very distinctive marker> score, and surname in common, I tentatively linked them as part of the same> group. When they had tested more markers in common they had a very strong> match. > > It is simplistic to judge "match" or "match falling apart at 25 markers" on> just the number of mutation steps difference. Context is very important.> > The larger surname projects become, the better the context is for comparing> two haplotypes. Two haplotypes compared in isolation, by someone not> experienced in interpreting DNA results, could be very misleading. The> added value of experience of the interpreter, is often even able to pick> "lab errors" in results. > > John.> > -----Original Message-----> From: > [mailto:] On Behalf Of > Sent: Monday, May 19, 2008 3:20 AM> To: > Subject: Re: [DNA] Y-DNA tEsting> > > In a message dated 5/18/2008 3:57:16 A.M. Central Daylight Time, > writes:> > Both my Clark, Smith, and Brown cousins have 12/12 matches with the same > surname that do not hold up at 25 markers. > > > > So those particular 12/12 matches are considered false positives?> > > No virus found in this outgoing message.> Checked by AVG. > Version: 7.5.524 / Virus Database: 269.23.20/1452 - Release Date: 5/17/2008> 6:26 PM> > > > -------------------------------> To unsubscribe from the list, please send an email to with the word 'unsubscribe' without the quotes in the subject and the body of the message

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