Can 5th cousins be genetic distance of 1?

[viofam]

Results for two participants in the Mallory DNA Project are a gnetic distance of 1.

Link to results:
http://www.familytreedna.com/(amv3y555ez4rtn45slqh50eb)/ftGroups_score_frame_classic.aspx?kit=D5615&SEQUEN CE=YES&SHOWKIT=True&SHOWLASTNAME=A&SHOWPREDICT=TRU E&AOL=False

Refer to the bottom two lines 10 & 11.
Kits #33799 & #37375 match all but marker 464c.
Their paper trails indicate they are 5th cousins.

Could they both have the same 4th great-grandfather, Thompson Mallory b abt 1725 VA d 1802 Hanover Co VA?

Is this possible or even likely?
Any replies will be appreciated.

[vineviz]

Results for two participants in the Mallory DNA Project are a gnetic distance of 1.

Refer to the bottom two lines 10 & 11.
Kits #33799 & #37375 match all but marker 464c.
Their paper trails indicate they are 5th cousins.

Could they both have the same 4th great-grandfather, Thompson Mallory b abt 1725 VA d 1802 Hanover Co VA?

Is this possible or even likely?
Any replies will be appreciated.

This DNA result would be perfectly compatible with the relationship you hypothesize. In fact, it is almost exactly what you would expect.

[viofam]

Thanks for the reply, Veneviz. I didn't want to waste too much time researching the paper trail if this was not the case.

[Itzhak Epstein]

Results for two participants in the Mallory DNA Project are a gnetic distance of 1.

Link to results:
http://www.familytreedna.com/(amv3y555ez4rtn45slqh50eb)/ftGroups_score_frame_classic.aspx?kit=D5615&SEQUEN CE=YES&SHOWKIT=True&SHOWLASTNAME=A&SHOWPREDICT=TRU E&AOL=False

Refer to the bottom two lines 10 & 11.
Kits #33799 & #37375 match all but marker 464c.
Their paper trails indicate they are 5th cousins.

Could they both have the same 4th great-grandfather, Thompson Mallory b abt 1725 VA d 1802 Hanover Co VA?

Is this possible or even likely?
Any replies will be appreciated.

If Bennett Greenspan, FTDNA's President, can be be at a genetic distance of 1 from his father and brother, so can these cousins.

[Bovon]

My 3rd cousin and I have a 0 genetic distance at 37 markers. He and I also have a genetic distance of 1 to another of our group..and God only knows how many generations separate us...at the very least, the CA was about 8 generations and about 250 years ago.

Max would be maybe 10 generations.

So, yes...a genetic distance of 1 for 5th cousins is very likely.

[viofam]

Thanks for the kind replies!

Both participants had their tests refined from 25 to 37 markers, revealing a total genetic distance of 3.
http://www.familytreedna.com/public/...xed_columns=on
In addition to the marker 464c difference,
they do not match at 576 and CDY a.

Is this also an expected or even possible result for 5th cousins or should we assume their common ancestor is further back than previously thought?

[MMaddi]

Thanks for the kind replies!

Both participants had their tests refined from 25 to 37 markers, revealing a total genetic distance of 3.
http://www.familytreedna.com/public/...xed_columns=on
In addition to the marker 464c difference,
they do not match at 576 and CDY a.

Is this also an expected or even possible result for 5th cousins or should we assume their common ancestor is further back than previously thought?

I think it's possible that you can regard the 3 mutations (464c, 576, CDYa) as actually only 2 mutations. This is because it may be that the differences at 464c and CYDa are linked through what is called a "recombinational loss of heterozygosity," also called a recLOH.

A recLOH occurs in multi-copy markers in the palindromic region. Any marker that ends in a letter is a multi-copy marker - 464a, 464b, 46c, 464d, CDYa, CDYb, etc. What happens is that one of the multi-copy markers overwrites its related mate, so that both have the same STR count.

So in the case of your two members, 33799 has 464a-d=12-15-15-16 and CDYa-b= 36-37, while 37375 has 464a-d=12-15-16-16 and CDYa-b=37-37. It looks quite possible that in some generation since these two lines diverged, an ancestor of 37375 had a recLOH event that involved both 464 and CDY. I have read that some believe that 464 and CDY can have one event that triggers an recLOH in both of them. This is because they are both located in the P1 palindromic region - see this illustration and look at the P1 region, where both 464 and CDY (also called 724) are located: http://www.dna-fingerprint.com/stati...cRegion-V2.pdf

Also, there was a posting on the Genealogy-DNA list at Rootsweb.com that will probably be of interest to you. It's by Gareth Henson, a very knowledgeable genetic genealogist. He comments on CDY and notes that it's considered a very fast mutator, aside from the possibility of recLOH. Here's the link for the posting - http://archiver.rootsweb.com/th/read...-03/1174773433 His e-mail address is there, so you can write him and ask him to take a look at your two member's results. He might be able to confirm what I've speculated about here and possibly tell you about some tests at FTDNA that may help you sort this out better.

Mike Maddi