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  #1  
Old 25th July 2014, 08:22 AM
COTEX COTEX is offline
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CDY marker

My 4th cousin tested recently to 111 markers. He matches two other 4th cousins also tested to 111 markers except on CDY-b. His haplogroup is R-M269. His value for CDY-b is 43 and the other cousins are 38. I don't know whether this is a fast moving marker or not. It just seems odd to be almost a perfect match but 5 steps off on this one particular marker. I was told lab errors do not usually occur so that is why I am wondering if this particular marker tends to mutate more than normal.
Thanks for any advice
-Carl
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  #2  
Old 25th July 2014, 09:25 AM
trifud trifud is offline
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CDY is fast mutating. It's mutation rate is 0.03531. If you doubt the test results, some companies provide testing for single STR markers. YSEQ offers it for $15.
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  #3  
Old 25th July 2014, 10:24 AM
COTEX COTEX is offline
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thanks, but the rate you indicated does not seem to account for a 5 step difference when the common ancestor is only 5 generations back. I guess I would have expected a higher rate to account for this.
-Carl
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  #4  
Old 25th July 2014, 11:18 AM
lgmayka lgmayka is offline
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Quote:
Originally Posted by COTEX View Post
thanks, but the rate you indicated does not seem to account for a 5 step difference when the common ancestor is only 5 generations back.
All markers are potentially susceptible to multistep mutations (multiple steps in one mutation), especially CDY a and b.
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  #5  
Old 25th July 2014, 12:06 PM
MMaddi MMaddi is offline
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CDY is what's known as a multi-copy marker, hence there are CDYa and CDYb values. DYS464a-b-c-d is another multi-copy marker.

The multi-copy markers are located on the palindromic arms of the y chromosome. Because of the configuration of these arms, the markers on them are subject to what's called "recombinational loss of heterozygosity" (RecLOH).

You can read about RecLOH at http://en.wikipedia.org/wiki/RecLOH#For_Y_chromosome The relevant quote is: "E.g. DYS459, DYS464 and DYS724 (CDY) are located on the same palindrome P1. A high proportion of 9-9, 15-15-17-17, 36-36 combinations and similar twin allelic patterns will be found... So a 9-10, 15-16-17-17, 36-38 haplotype can change in one recombination event to the one mentioned above, because all three markers (DYS459, DYS464 and DYS724) are affected by one and the same recLOH event." In other words, a RecLOH can easily turn CDYa-b=36-38 in one mutation into 38-38."

It's possible that the two 4th cousins with CDYb=38 originally had the CDYb=43 of the other 4th cousin, but that a RecLOH overwrote the marker to make it 38 - all in one mutation. Is it the case that the two cousins have CDYa-b=38-38 and the other cousin has CDYa-b=38-43? That would support a RecLOH being responsible for a 5 step difference among the cousins.
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  #6  
Old 25th July 2014, 01:05 PM
Stephen Parrish Stephen Parrish is offline
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Quote:
Originally Posted by MMaddi View Post
CDY is what's known as a multi-copy marker, hence there are CDYa and CDYb values. DYS464a-b-c-d is another multi-copy marker.

The multi-copy markers are located on the palindromic arms of the y chromosome. Because of the configuration of these arms, the markers on them are subject to what's called "recombinational loss of heterozygosity" (RecLOH).

You can read about RecLOH at http://en.wikipedia.org/wiki/RecLOH#For_Y_chromosome The relevant quote is: "E.g. DYS459, DYS464 and DYS724 (CDY) are located on the same palindrome P1. A high proportion of 9-9, 15-15-17-17, 36-36 combinations and similar twin allelic patterns will be found... So a 9-10, 15-16-17-17, 36-38 haplotype can change in one recombination event to the one mentioned above, because all three markers (DYS459, DYS464 and DYS724) are affected by one and the same recLOH event." In other words, a RecLOH can easily turn CDYa-b=36-38 in one mutation into 38-38."

It's possible that the two 4th cousins with CDYb=38 originally had the CDYb=43 of the other 4th cousin, but that a RecLOH overwrote the marker to make it 38 - all in one mutation. Is it the case that the two cousins have CDYa-b=38-38 and the other cousin has CDYa-b=38-43? That would support a RecLOH being responsible for a 5 step difference among the cousins.
Mike and Larry -

If a RecLOH event produces CDY=38-38, to what extent is that event reversible? I am aware that DYS425=null is apparently irreversible, unless someone's recent discovery supports a different conclusion.

Stephen
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  #7  
Old 25th July 2014, 01:36 PM
MMaddi MMaddi is offline
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Quote:
Originally Posted by Stephen Parrish View Post
Mike and Larry -

If a RecLOH event produces CDY=38-38, to what extent is that event reversible? I am aware that DYS425=null is apparently irreversible, unless someone's recent discovery supports a different conclusion.

Stephen
I think it would be hard to be reversible. There would have to be at least two mutation events to reverse it.

We have CDY=38-38 from a RecLOH event. Then there would have to be another mutation, let's say CDYb mutates in a later generation to 39. Then in another later generation a RecLOH turns the CDY=38-39 to 39-39.

CDY has a relatively high mutation rate, but that's still two more mutation events to get to 39-39.
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  #8  
Old 25th July 2014, 01:50 PM
1798 1798 is offline
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Quote:
Originally Posted by COTEX View Post
My 4th cousin tested recently to 111 markers. He matches two other 4th cousins also tested to 111 markers except on CDY-b. His haplogroup is R-M269. His value for CDY-b is 43 and the other cousins are 38. I don't know whether this is a fast moving marker or not. It just seems odd to be almost a perfect match but 5 steps off on this one particular marker. I was told lab errors do not usually occur so that is why I am wondering if this particular marker tends to mutate more than normal.
Thanks for any advice
-Carl
You have nothing to worry about. My brother does not match me exactly in haplotype but he is my brother. I am 100% sure of that.
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  #9  
Old 25th July 2014, 08:59 PM
Stephen Parrish Stephen Parrish is offline
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Quote:
Originally Posted by MMaddi View Post
I think it would be hard to be reversible. There would have to be at least two mutation events to reverse it.

We have CDY=38-38 from a RecLOH event. Then there would have to be another mutation, let's say CDYb mutates in a later generation to 39. Then in another later generation a RecLOH turns the CDY=38-39 to 39-39.

CDY has a relatively high mutation rate, but that's still two more mutation events to get to 39-39.
Mike -

Thank you very much for your reply, with which I concur.

Stephen
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  #10  
Old 26th July 2014, 01:01 PM
COTEX COTEX is offline
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Stephen,
Thanks for the explanation. I need to read up on the RecLOH you mentioned. To answer your question, yes the two other 4th cousins have identical markers for CDY. Also other close matches with the same surname have the same. Its just this one cousin with the different result. I was not aware that a single mutation could make that big a difference in a single marker.
-Carl
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