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Archiver > GENEALOGY-DNA > 2010-03 > 1269389746


From: Harold Vannoy <>
Subject: [DNA] Comparing FGS and 23andMe mtDNA Tests - Results Don't Agree
Date: Tue, 23 Mar 2010 20:16:15 -0400


I have finally received my FTDNA mtDNA-FGS test results (ordered the
second week of October). I am now comparing the FGS test results to
my 23andMe mtDNA test results. This comparison has brought to light
many questions. The most troubling find is that the test results from
the two companies don't agree at some locations.

The "location" (position) given in the 23andMe mtDNA test results IS
NOT the "rCRS" position, but is related to a "Yoruba" reference. The
corresponding rCRS number is, however, given in parenthesis for each
position in the 23andMe "Browse Raw Data" web pages.

One question that I have relates to SNP results that are given in the
23andMe data that I can't find in the FGS results. The 23andMe
positions are the same as the rCRS positions up through 23andMe
position 304. On the "Browse Raw Data" page, position 310 does not
have a corresponding rCRS number! The same is true for position 311.
The two readings given at position 317 are shown to correspond to
rCRS 315 (a difference of two in the readings).

Position (rCRS) SNP Versions "my" Genotype
304 (304) i4001202 C or T C
310 () i4001204 A or C C
311 () i4001008 C or T C
317 (315) i4001006 C or T C
317 (315) i4001007 C or T C

My question is this: Why don't the SNPs at 23andMe positions 310 and
311 show in my FGS (FULL GENOME Sequence) results or, if they do,
where are they? There is a specific "RSID Number" and "Genotype"
given for each of these positions.

Another question: Why do I have two readings for 23andMe position 317
(and at numerous other positions - sometimes there are three readings
for a specific position)? Are these "repeats" of the same SNP and,
if so, why don't they show in my FGS results?

The difference of two in the readings between the 23andMe position
and the rCRS continues until somewhere between 23andMe positions 3103
and 3117. The difference between the readings then drops to one. Why
did this change occur?

3103 (3101) rs28416306 A or C A
3117 (3116) i4001013 C or T C

The difference of one from the rCRS reading continues through 23andMe
position 16183. There are then three readings for position 16184 that
do not have a corresponding rCRS number. The difference between
readings becomes two again at 16186. Again, where are the three SNPs
relating to 23andMe position 16184 in my FGS results?

16183 (16182) i4001307 A or G A
16184 () rs28671493 A or C A
16184 () i4001306 A or C A
16184 () i4001305 A or C A
16186 (16184) rs34100702 C or T C

My most troubling find has been that I get different genotype
readings for some of the SNPs on the two test results from the two companies:

FGS rCRS Genotype 23andMe Corresponding rCRS Genotype
185 A 185
T
825 T 825
C
3552 T 3552
A
8285 C 8285
I
15884 G 15884 (2nd SNP at this position) T
16093 T 16093
A
16129 G 16129 (2nd SNP at this position) C

How can I determine which value is correct?

Thanks in advance.

Harold Vannoy


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