Using T-SNPs

Note: I am calling Terminal SNPs "T-SNPs" so that the label will fit into a smaller space

Many researchers are finding that two men who they know to be closely related have different T-SNPs (Terminal SNPs) and they are asking about this difference.

First - let's talk about the color of the reported T-SNP

  • Green - T-SNP based on formal test of the SNP
  • Red - FTDNA estimate of the T-SNP - based on marker match to a man formally tested to the SNP
  • Black - a definition of the T-SNP from someone other than FTDNA

My suggestions:

  1. Look up TT-SNP on the ISOGG Tree at http://isogg.org/tree/index.html   (Note that I use the ISOGG long form in the examples below so that you can see the implication of a specific T-SNP)
  2. Give more credence to a green T-SNP than to red or black
  3. Be very careful - as this is much more confusing that it should be!

Let's discuss some of the scenarios:

There are two general cases where a different T-SNP means that two men cannot share recent common ancestry

  1. When each man's T-SNP is on a distinctly dufferent branch of the tree

    1. Definitive If both T-SNPs are green and they are clearly on different branches.  Example:

      1. R-P312 (R1b1a2a1a2)
      2. R-U106 (R1b1a2a1a1)
    2. Probably definitive if one or both T-SNPs are red - BUT if the two men are matching with ySTR (markers), I'd ask FTDNA to review their estimate(s) or even get a formal SNP test to confirm the FTDNA estimate(s)
  2. When one man is Positive for a SNP and the other is negative (unless it's the very last branch on the tree)

    1. The man who is positive will have the SNP shown in green
    2. The man who is negative for the SNP will be reported with some other T-SNP
    3. You will not know about the man who is negative for that SNP unless you have special knowledge

      1. Someone has told you the man is negative
      2. You are able to look it up on the ySNP page in the Project's FTDNA public pages
    4. Example:

      1. U152+ will be reported as R-U152 (R1b1a2a1a2b)
      2. U152- may be reported as R-P312 (R1b1a2a1a2) or even as something else like R-M269
      3. Unless you know the man is U152-, his R-P312 is simply one step up on the tree from R-U152 and they look related

HOWEVER - two men known to be closely related can be reported with different SNPs simply because they are one different in marker matching and the men they match were tested to two different SNP levels. (or because they were SNP tested to a different level. 

Real Examples where the different T-SNPs are allowed to be in the same Lineage:

  • From Crabbe (provoked this Blog Posting)

    • R-U106 (red) (R1b1a2a1a1)
    • R-L47   (red) (R1b1a2a1a1c2b1)
  • From Barton

    • R-P25  (green) (R1b1)
    • R-M269 (red)   (R1b1a2)
    • R-P312 (red)    (R1b1a2a1a2)
    • R-U152 (green) (R1b1a2a1a2b)
    • R-L2     (green) (R1b1a2a1a2b1)
    • R-L196   (green) (R1b1a2a1a2b1b)

Note: don't get too excited if your T-SNP isn't on the ISOGG yTree - as the lack of correlation will continue for a while, but shoulkd be reduced as FTDNA refines their structure and ISOGG checks out branches FTDNA has found.

SO - IF IN DOUBT - ASK !!!!  And - since FTDNA has created this un-necessary confusion - ask their Helpdesk instead of your Project Administrator.

Terry

Hoppers from Virginia

I have posted my line under the patriarch's page. I have a theory on the parents of "my" Beverly Hopper b. about 1774 in VA; married to Sarah Miller; both died between 1850-1860 probably in Miami County IN as they are in the 1850 IN Miami County, Census.

Through VA chancery court records I can confirm that a John Hopper born about 1736 (unknown place) and died about 1803 in KY was married to Anna? He leased land to another ancestor of mine - Peter Hitt - in the Manor of Leeds - Fauquier County, VA. John's son is named Humphrey Hopper who died during the Rev. War. I have documents showing that this Humphrey provided supplies to the colonies during the war. He was located in Shenandoah County. Humphrey had a daughter named Sarah ?? who married a Clendenning. I cannot find any further evidence of his off-spring. "My" Beverley Hopper would be the proper age to be Humphrey's son. Also, Beverley named one of his son's Humphrey -- a uncommon name in the VA records.

I am wondering if my theory could be correct. If I can ever find a male Hopper from my family (and there should be lots of them), I would be happy to finance the Y-DNA test to help eliminate the other Hopper families. I would like to have your opinions on my theory.

Thank you, Sherri Manker