Monday, 24 September 2012

Family Tree DNA to introduce terminal SNP label for Y-DNA

Further to CeCe Moore's blog post advocating the adoption of a terminal SNP label rather than the longhand currently employed to define Y-DNA haplogroup/subclade, Family Tree DNA have now inserted an explanation on their user's Haplotree page. It states:

Important Notice
Long time customers of Family Tree DNA have seen the YCC-tree of Homo Sapiens evolve over the past several years as new SNPs have been discovered. Sometimes these new SNPs cause a substantial change in the “longhand” explanation of your terminal Haplogroup. Because of this confusion, we introduced a shorthand version a few years ago that lists the branch of the tree and your terminal SNP, i.e. J-L147, in lieu of J1c3d. Therefore, in the very near term, Family Tree DNA will discontinue showing the current “longhand” on the tree and we will focus all of our discussions around your terminal defining SNP.

This changes no science - it just provides an easier and less confusing way for us all to communicate.


Bennett Greenspan, Family Tree DNA

Dr. Michael Hammer, University of Arizona

My own longhand label is currently R1b1a2a1a1b5b, but my terminal SNP is R-L165. R being haplogroup R and L165 the terminal SNP which was discovered by Dr Jim Wilson who named it S68. R-L165 is certainly much easier to remember. Of course many testee's do not know their terminal SNP perhaps unaware that their deeper ancestry can also be explored and rely solely on the haplogroup backbone test included as part of their 37 or 67 marker STR (Short Tandem Repeat) test.  

It is often not possible using STRs alone to identify a subclade as STR alleles (markers) can mutate back and forth, while a SNP mutation is a once only event carried by all subsequent descendants. This makes SNP testing ideal for surname studies.

Family Tree DNA are in the process of replacing their current 'deep clade' test which uses approximately 900 SNPs to identify a terminal SNP, with the 12,000 Y SNPs which are part of the new Geno 2 product for the National Genographic Project which launches in October (Family Tree DNA are continuing to undertake the testing for the Genographic project.)

Deep clade testing using SNPs no longer just identify deep ancestral origin and migration thousands of years ago, but is very much on the threshold of the period when surnames were being created and fixed.

Is this important? With cost effective full genome sequencing not too far away we are already seeing the discovery and use of a terminal SNP to define and link a surname and specific lineage. In the future with full sequencing of the Y-Chromosome there will be a specific SNP linked and identifiable with a specific surname and lineage, this will continue the opportunities for Y-DNA to push back genealogies into the medieval period and overcome brick walls.

Surname and one-name studies has just moved up another notch.

email: alasdair@yourscottishancestry.com 
Professional Genealogy Research Service

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