Saturday, February 10, 2018

The Strange Case of the Missing Y37 Match



 
The other day the subject arose in a Facebook group about the possibility of matching someone at 67 Y-STR resolution while simultaneously not matching that same person at 37 markers. The conclusion was that this was a rare occurrence.  

In our project, several participants were not matching documented relatives with the same surname at 37 markers, but they had subsequently matched these same individuals at 67 markers; I realized that this was a significant occurrence in, at least, our project and set out to see if it included non-family members as well.

SURNAME PROJECT BACKGROUND


Since the 1970s, three researchers have been cataloging past and present descendants of two extant and three extinct families with our surname that ramified in what is now the Ryedale District of the present county of North Yorkshire, England.  It is estimated by counting the number of cataloged males that 296 exist to the present.  With a 5% margin of error, that number increases to 311.  We are a very low frequency surname that has three current variations Owston (72%), Ouston (26%), and Owston-Doyle (2%). 

The Owston/Ouston DNA project began in 2010 and has risen to 33 Y-DNA participants.  About 10.6% of the entire male population of our surname has had their Y-DNA tested. Not counted in this percentage are six other Owston males who have tested autosomally and most certainly match the surname haplotype due to matching autosomal DNA to those who have tested their Y-DNA.  Four of these males have been identified as having the I1 (I-M253) haplogroup via 23andMe.  Our participants were recruited from the United States, England, Canada, New Zealand, Australia, and Finland.  Including all autosomal participants, we have 62 members total.

Of our 33 Y-STR participants, ten have a paper ancestry to one of the two extant families, but these ten have ancestral non-paternal events and do not match the family modal haplotype.  Five of the remaining 23 tested at GeneTree with a 43-marker test between 2010-2012.  The remaining 18 have all tested at Family Tree DNA at 111 markers. In addition, 15 have tested with the Big Y (with two tests pending).   

Of the 18 participants, there are 153 relationships that range from a sibling pair to 13th cousins, twice removed. Relationships of 12th cousin and beyond are estimated due to onomastic evidence linking the two families to a common source born in the latter half of the 15th century; the closest possible relationship is used for the estimates; the relationships should be no further than two additional generations than our estimation.  

The first documented use of the surname in the region dates to 1452. Big Y participants from both families share A10206 and 14 additional phylogenetic SNPs. The Sherburn family (including its Cobourg and Ganton subsets) all share BY31751, while the Thornholme family members share the A15739 SNP. 

67-MARKER MATCHES ABSENT AT 37 MARKERS


In analyzing the matches of 18 matching FTDNA Y-STR participants in the Owston/Ouston DNA study, 100% of the men who tested at 67 markers matched at least one individual who was not found in their 37-marker match list. The numbers ranged from one to six non-matching individuals at 37 markers with the average being 3.77.  The percentage of non-matches at 37 within the 67-marker match list ranged from 3.6% to 35.3% of their total 67-marker matches.  An average of 14.1% of their 67-marker matches were absent from their 37-marker match list. 

The following table shows the total matches at 67 markers and the number of these matches that are missing from their 37-marker list. A percentage of the whole is also provided. 


KNOWN FAMILY 67-MARKER MATCHES ABSENT AT 37 MARKERS


Eight of our 18 participants (44.4%) had non-matches with a family member at 37 markers.  This is a significant number and can be greatly attributed to a person’s genetic distance from the family modal haplotype. Even a genetic distance of 1 when paired with a genetic distance of 4 will produce an absence of a match at 37 markers.  This is a factor that could be extremely important to genetic genealogists, as there may be a matching family member at 67 markers that does not show in the participant’s list at 37. 

The following table provides an analysis of missing family members at 37 markers.  In order to understand this phenomenon, the participant’s genetic distance from the surname model haplotype is listed.  Each person should have 17 matching family members at 37 markers; however, eight individuals are missing one or several matches to family members they match at 67 markers.   

 
The absent family members at 37 markers in our project included the following relationships:

  • One seventh cousin, once removed pair;
  • One seventh cousin, twice removed pair;
  • Two eighth cousin, once removed pairs;
  • One eighth cousin, twice removed pair;
  • Two ninth cousin pairs;
  • One ninth cousin, once removed pair;
  • One ninth cousin, thrice removed pair; and 
  • Three tenth cousin, twice removed pairs.  

The 12 relational pairs represent 7.8% of the total number of matching family relationships (153) at 67 markers.   

An interesting development with absent matches at 37 markers is that this phenomenon occurred intra-family within the Sherburn family and was not present with matches to the more distantly related Thornholme family.  Some of this may be attributed to a lack of viable participants within the Thornholme family. 

Although the Thornholme family is rather small with only 25 living males, all four lines have been tested.  Of the 25 aforementioned males, 14 have non-paternity events within their ancestries.  Of the 11 potentially remaining matching members, three have tested (one at 43 markers).  The other eight are closely related to at least one participant who has already tested. Among those not tested, the most distant relationship is that of a first cousin, twice removed.  It is not likely that any new data would be gained in further testing any of the remaining eight Thornholme men.

CONCLUSION


Do not discount the possibility that match may exist at 67 markers but be absent at 37 markers.  In our family, 100% of our participants were missing at least one 67-marker match at 37 markers. Forty-four percent of our participants were missing at least one family member at 37 markers.  One participant was missing six and another missing five family members.  

While the data presented has a small sample size and is only indicative of our singular family project, the results may differ from the general population of FTDNA Y67 results. Therefore, it is suggested that a similar analysis be replicated within a haplogroup project to see if the results are consistent.  

6 comments:

  1. Very interesting. Do you have any idea why this is occurring? Are the same 37 marker locations included in the 67 marker locations? If so, have you inquired at FTDNA what the reason is for this? Thank you

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    1. Mutations are random and for some of the more distance matches, it may be a result of convergence. The 37 markers are also part of the larger 67 markers.

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  2. Each surname study will be different in results. Some studies I have looked at have so many different and ongoing mutations I would doubt one could make a whole lot of determinations. In my surname group I looked at the Total results and found no loss of testers from one bank to the next bank ....meaning from 37 to 67 to the 111. I have 83 matches at the 37 point level,all at GD of 5 or less. No testers were listed more than GD of 5. Of those 83 a total of 45 testers did not upgrade. That leaves 38 testers that did upgrade. Shown at the 67 point level I have 38 matches. Same matches as the 37 minus the 45 who did not upgrade. These 67 point matches were up to and a GD of 5. In the 111 matches,I show 17 matches . Of the 67 point testers who did not upgrade were 20. We have lost a tester here from 67 to 111. The GD of the 111 were up to GD of 8. As far as my test group...there were no testers who showed at 67 or 111 who did not show at a 37 point readout. A tester within a study who does so would IMO be a rare occurence.

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    1. Every grouping is different. How many were sampled in your surname group? In our case, everyone of our participants lost at least one person. A GD=5 should not show at 37 markers even when related, but will show at 67 markers. I'm hearing from others that are seeing this with their results. My caveat is that this is one study and one study alone. More need to be documented before it can be determined how prevalent this phenomenon is.

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  3. You are correct,my post should have said all at GD of 4 or less at the 37 point level. Our group is Total of the 83 37 point matches plus 12 and 25 point members. All testers are from a MRCA b @ 1685. This would include at least 4 different surnames who have found their link to the main surname.

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    1. Thanks for the clarification Michael.

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