GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2005-03 > 1112201518
Subject: Re: [DNA] Newbie J2 questions
Date: Wed, 30 Mar 2005 11:51:58 EST
In a message dated 03/29/05 8:47:20 PM Pacific Standard Time,
> A search for matches among FTDNA customers produced NO exact matches at
> either 12 or 25 markers. I assume the addition of the remaining markers
> will not change this. They did show 2 at a distance of 2, +3 at a distance
> of 3, +6 at a distance of 4, and +19 at a distance of 5. The following
> possibilities occur to me.
> 1. There are no FTDNA exact matches.
> 2. There may be FTDNA exact matches, but those people have not authorized
> release of their information.
> 3. FTDNA has made some kind of mistake.
The most likely explanation is #1, because of "haplotype diversity." Your
haplotype is the set of results on whatever markers were tested. The European
section of the database at http://yhrd.org has 18,711 records -- and 8,497
distinct haplotypes! That means there are many haplotypes which appear only once.
And that's mostly based on just 9 markers -- as you add more markers, the number
of exact matches keeps going down. Every time a new batch of records is added
to YHRD, there will be some novel haplotypes that hadn't been sampled yet.
Sometimes you will differ from the modal values (single most common values)
for a haplogroup by just one step on one or several markers. That's enough to
markedly reduce the number of matches. For example, there are 24 different ways
you can differ by one step from the modal haplotype on a 12-marker test.
You can check YHRD or the statistics page at http://ybase.org to see if any
of your markers seem out of the usual range.
Ann Turner - GENEALOGY-DNA List Administrator
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