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  #1  
Old 4th January 2014, 10:23 AM
Special25 Special25 is offline
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Phasing Question

Sadly, my inlaws have passed away, but is there a way to phase the results of their four children to build up an image of what their DNA profile would have been, or does it require one of the parents to provide a sample?

When looking at AtDNA results, can you separate one chromosome from the other or does it treat each pair as a single entity?

I am assuming that if we could separate the two chromosomes from each pair, you would theoretically be able to rebuild most of the missing data from the two parents and use a cousin of ethnic background match to confirm which chromosome from each pair came from which parent.

Pipe dream or realistic??
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  #2  
Old 4th January 2014, 01:11 PM
ajmr1a1 ajmr1a1 is offline
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Quote:
Originally Posted by Special25 View Post
Sadly, my inlaws have passed away, but is there a way to phase the results of their four children to build up an image of what their DNA profile would have been, or does it require one of the parents to provide a sample?

When looking at AtDNA results, can you separate one chromosome from the other or does it treat each pair as a single entity?

I am assuming that if we could separate the two chromosomes from each pair, you would theoretically be able to rebuild most of the missing data from the two parents and use a cousin of ethnic background match to confirm which chromosome from each pair came from which parent.

Pipe dream or realistic??
If you have both a male and female sibling to test, you can phase the x-chromosome. NB: The male child gets his x-chromosome from his mother.
The female child gets one "X" from her Mom (identical to her brother's X)
and one "X" from her Dad.

http://linealarboretum.blogspot.com/...hromosome.html

Phasing the rest of the atDNA would require testing all 4 siblings and many
1st and 2nd cousins.

Rob Warthen at www.dnaAdoption.com is an expert on phasing.
He could tell you more about what would be required.

I hope this helps.
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  #3  
Old 5th January 2014, 12:35 PM
prairielad prairielad is offline
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Quote:
Originally Posted by ajmr1a1 View Post
If you have both a male and female sibling to test, you can phase the x-chromosome. NB: The male child gets his x-chromosome from his mother.
The female child gets one "X" from her Mom (identical to her brother's X)
and one "X" from her Dad.

http://linealarboretum.blogspot.com/...hromosome.html

Phasing the rest of the atDNA would require testing all 4 siblings and many
1st and 2nd cousins.

Rob Warthen at www.dnaAdoption.com is an expert on phasing.
He could tell you more about what would be required.

I hope this helps.
Not sure if a typo, but the mother has two X's which recombine randomly for each child, this X from mother will not be identical in any of the children when comparing them against one another, possible but highly unlikely.
All female children of the Father will have the identical X of Father, as he only has one, therefore all female siblings will have one identical X with each other.
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  #4  
Old 5th January 2014, 02:11 PM
MMaddi MMaddi is offline
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Quote:
Originally Posted by prairielad View Post
Not sure if a typo, but the mother has two X's which recombine randomly for each child, this X from mother will not be identical in any of the children when comparing them against one another, possible but highly unlikely.
All female children of the Father will have the identical X of Father, as he only has one, therefore all female siblings will have one identical X with each other.
I agree. The mother gets two x chromosomes, one from each of her parents. They can recombine and the mother passes whatever recombined x chromosomes she has to her children.

I have read that the child can get the unrecombined x that came from the maternal grandmother or maternal grandfather, but this is rare. In most cases, the x that a child receives from the mother will be a recombination of the x's she received from her parents. In this case, the mother's various children can receive different x's from her or, in rare cases, the exact same x from one of the maternal grandparents.

Here's a real life example. My sister and I share two segments on the x, one of 44.0 cM and the other 9.3 cM. I see this in Family Inheritance: Advanced in my 23andMe account. In mb, the first segment is from 53 million to 118 million and the second one is from 149 to 155. That leaves a lot of the x (I only have one) where we didn't receive the same DNA.
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  #5  
Old 5th January 2014, 07:03 PM
prairielad prairielad is offline
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Quote:
Originally Posted by Special25 View Post
Sadly, my inlaws have passed away, but is there a way to phase the results of their four children to build up an image of what their DNA profile would have been, or does it require one of the parents to provide a sample?

When looking at AtDNA results, can you separate one chromosome from the other or does it treat each pair as a single entity?

I am assuming that if we could separate the two chromosomes from each pair, you would theoretically be able to rebuild most of the missing data from the two parents and use a cousin of ethnic background match to confirm which chromosome from each pair came from which parent.

Pipe dream or realistic??
Yes and No

This all depends how much of each grandparent is represented in each sibling. ie mothers DNA consist of her paternal and maternal chromosome which recombined to child.
To get the best coverage of parents DNA each grandparents DNA has to be represent at each position of each chromosome.

If only 4 siblings have tested you will not be able to determine which is parent A on Chromosome 1 vs parent A on any of the other chromosomes. Parent labelled A on one chromosome may be labelled Parent B on next. This is where having an Aunt/Uncle or cousin tests helps in identifying which is which parents DNA as well as keeping it labelled correctly going from 1 chromosome to the next.

I am currently trying to determine my paternal grandparents DNA, specifically my paternal grandmother. So far I have tested both my parents, a maternal uncle, a paternal uncle, a paternal Aunt, my fathers paternal 1st cousin, and myself and 4 other siblings. Hoping to test 3 more of my fathers siblings.

Attached is the percentage of each of my paternal grandparents DNA per chromosome I have been able to determine by comparing all of the above together in a spreedsheet based on their shared sections . I have only got to chromosome 5 so far.

Parent A and Parent B represent my fathers Grandparents, which is only a representation of half that grandparents DNA (Half that his mother and father received)

Edit
Also note that as mentioned above Parent A could be represented as Parent B on next chromosome in picture. At this point only able to determine which are my father's mothers and fathers values. Which maternal or paternal grandparent is which can not be determined when crossing to next chromosome.

Last edited by prairielad; 24th February 2014 at 03:11 PM.
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  #6  
Old 5th January 2014, 07:39 PM
prairielad prairielad is offline
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I will also add that to my advantage in phasing each of my grandparents are from unrelated populations back to at least the mid 1700's
Maternal Grandmother was English
Maternal Grandfather had a Norwegian born father and Swedish born Mother.
Paternal Grandmother was born in Romania with German background
Paternal Grandfather had Scottish father and Irish mother.
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  #7  
Old 6th January 2014, 05:34 PM
Special25 Special25 is offline
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Many thanks. Sounds like the possibility is there, even if we recover just 75% of the data.

Worth getting us all tested and there are some cousins and one aunt around to help. I wasn't even entirely sure that you could differentiate between the two chromosomes in a pair, so it's all encouraging news!!
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  #8  
Old 6th January 2014, 07:01 PM
ajmr1a1 ajmr1a1 is offline
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Quote:
Originally Posted by prairielad View Post
Not sure if a typo, but the mother has two X's which recombine randomly for each child, this X from mother will not be identical in any of the children when comparing them against one another, possible but highly unlikely.
All female children of the Father will have the identical X of Father, as he only has one, therefore all female siblings will have one identical X with each other.
Right. Typo!

You expressed this clearer than I did.
Thanks.
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