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  #1  
Old 2nd December 2014, 12:33 PM
Tenn4ever Tenn4ever is offline
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FMS genetic distance 1

I have seven matches at the FMS level but the genetic distance is "1". What is a genetic distance of '1' ? I understand the genetic distance on Y testing but can't seem to wrap my mind around it on the FMS.
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Old 2nd December 2014, 01:33 PM
1798 1798 is offline
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Originally Posted by Tenn4ever View Post
I have seven matches at the FMS level but the genetic distance is "1". What is a genetic distance of '1' ? I understand the genetic distance on Y testing but can't seem to wrap my mind around it on the FMS.
You have one SNP difference to your match. The SNP rate for MTDNA could be 3,700 years per SNP. So an exact match would leave you related within 3,700 years and in your case with one mutation it would be 7,400 years.
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Old 2nd December 2014, 03:17 PM
Tenn4ever Tenn4ever is offline
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Originally Posted by 1798 View Post
You have one SNP difference to your match. The SNP rate for MTDNA could be 3,700 years per SNP. So an exact match would leave you related within 3,700 years and in your case with one mutation it would be 7,400 years.
Thank you. Yes, the FMS MtDNA is about as useless as I thought
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Old 2nd December 2014, 03:22 PM
LynCra LynCra is offline
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Might be worth waiting until some more knowledgable people add to the thread before you draw a conclusion. I have a GD of 1 to my aunt so you cannot take 7400 years as the only interpretation.
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Old 2nd December 2014, 03:24 PM
Tenn4ever Tenn4ever is offline
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Originally Posted by LynCra View Post
Might be worth waiting until some more knowledgable people add to the thread before you draw a conclusion. I have a GD of 1 to my aunt so you cannot take 7400 years as the only interpretation.
Thank you. I wish FT would put this in the 'learning area'. I've searched and there's nothing.
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Old 2nd December 2014, 09:09 PM
GST GST is offline
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Quote:
Originally Posted by LynCra View Post
Might be worth waiting until some more knowledgable people add to the thread before you draw a conclusion. I have a GD of 1 to my aunt so you cannot take 7400 years as the only interpretation.
There is also a case of a woman who is 3 step match with her mother and a 4 step match with her sister (all three tested the FMS). So there is no simple answer and I would not try to predict the significane of a 1 step match without more information- you need to look a the age of your subclade, the number of extra mutations in your line, and at which markers the mismatch occurs (heteroplasmy? fast mutating site?). Matches can be quite recent or very ancient.

Last edited by GST; 2nd December 2014 at 09:11 PM.
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  #7  
Old 2nd December 2014, 11:03 PM
dna dna is offline
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@GST

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Originally Posted by GST View Post
There is also a case of a woman who is 3 step match with her mother and a 4 step match with her sister (all three tested the FMS). [----]
Can you please tell us more?

Was heteroplasmy involved?

Which positions were different?

Thank you!

W.
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Old 3rd December 2014, 04:52 AM
1798 1798 is offline
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Originally Posted by Tenn4ever View Post
Thank you. Yes, the FMS MtDNA is about as useless as I thought
The estimate of 3,700 years per MTDNA mutation comes from Dr Behar. MT Eve is said to have originated 200,000 years ago and the average number of MTDNA mutations is 55. We know how family members are related to us but we don't know how closely strangers are related to us by MTDNA.
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  #9  
Old 3rd December 2014, 10:57 PM
GST GST is offline
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Quote:
Originally Posted by 1798 View Post
The SNP rate for MTDNA could be 3,700 years per SNP. So an exact match would leave you related within 3,700 years and in your case with one mutation it would be 7,400 years.
If the common ancestor of two peole was 3700 years ago, you would expect each person to have 1 new mutation, so that would be a two step difference. For a common ancestor 7400 years ago you would expect a 4 step difference, on average, but the mutation rate is highly varible. Some lines will accumulutate 10 or more mutations in 7400 years while others will have none, so you can't apply average statistics to individual cases. You need to look at the specific mutations in each person.
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Old 3rd December 2014, 11:05 PM
GST GST is offline
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Originally Posted by dna View Post
Can you please tell us more? Was heteroplasmy involved? Which positions were different?
I can't share specific details but the 4 step difference between mother and daughter included 1 new mutation in the daughter, one heteroplasmy, and a difference at a higly volatile marker (that is excluded from Phylotree) that was counted as 2 steps.
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