GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2007-07 > 1184106619
Subject: Re: [DNA] SMGF mtDNA Question
Date: Tue, 10 Jul 2007 18:30:19 EDT
In a message dated 7/10/2007 3:15:41 PM Pacific Daylight Time,
> I just got my mtdna results. They were the same as my results at Family
> Tree DNA except I had a deletions at 160522 and 160523 at FTDNA. SMGF has
> my deletions at 160523 and 160524, and 160522 doesn't appear. Is this a
> typographical error or a difference in lab nomenclature?
I think you mean 522, not 160522 (etc.).
The deletion of two base pairs in this region has been reported in different
ways at different times. Even FTDNA changed its method midstream (I don't
recall quite when).
The ambiguity arises because there is a section in the CRS starting at 514
that reads cacacacacac. This is like a Short Tandem Repeat on the Y chromosome,
and insertions/deletions of two bases are rather common. But -- is the repeat
pattern CA (starting at 514 and ending at 523) or is it AC (starting at 515
and ending at 524)? SMGF uses the second method, which happens to be the one
recommended by the FBI for its forensic database, but several conventions have
been used in the literature. Some sources even will say the deletion occurred at
the beginning and record it as 514- 515-.
Obviously, we can't know which two bases were deleted, so it's just a matter
of convention on how to place them. For matching purposes, just consider
whether there are deletions of two bases in that vicinity.
See what's free at http://www.aol.com.