Standard ID for Triangulated Groups

A Segment-ology TIDBIT

In my spreadsheets and notes and analyses, I refer to Triangulated Groups (TGs) by a special ID name for each one.  For example: TG 01S24 breaks down as follows:

01 means Chromosome 01 – this TG is on that Chromosome

S indicates, roughly, how far out on that Chromosome the TG starts. Each letter is roughly 10Mbp wide. “A” means the TG starts between base pair 1 and base pair 10,000,000 (or 10Mbp); “B” means the TG starts between 10 and 20Mbp; “S” means the TG starts between 180 and 190Mbp. In fact, my TG 01S24 covers 182-229Mbp; and the next TG along Chromosome 01 is 01X24. I’m not a slave to this “rule,” and adjust where it makes sense. NB: Everyone will have a uniquely different chromosome map, and their TGs will have different locations.

24 indicates the grandparent in Ahnentafel. When I can determine a TG is on my Paternal or Maternal side, I use 2 or 3 respectively. When I can determine the TG is on a particular grandparent, I use 24, 25, 36 or 37. I only carry it out two generations (so far). NB: some people use P or M (for Paternal or Maternal), instead of Ahentafel numbers – take your pick.

If I’m referencing a Match, I might add the cM to show how significant the Match is in the TG. For example, Match A with 01S24, 38.7cM is much more significant than Match B with 01S24, 9.3cM. Clearly Match A is more likely to be a closer cousin (maybe a 4th or 5th cousin) than Match B (maybe well beyond my genealogy Tree)


Give each TG an ID

01S24 = A TG on Chromosome 01; starts 180-190Mbp; mapped to father’s father’s line

01S24, 38.7cM = A Match segment in TG 01S24 which is 38.7cM.


[22X] Segment-ology: Shorthand ID for Triangulated Groups TIDBIT; by Jim Bartlett 20190202

7 thoughts on “Standard ID for Triangulated Groups

  1. Pingback: Wlaking the Clusters Back (WTCB) 2022 | segment-ology

  2. Pingback: The Life of a DNA Segment | segment-ology

  3. Pingback: TG SUMMARY Spreadsheet | segment-ology

  4. Pingback: Walking The Clusters Back | segment-ology

  5. Pingback: D I Y Clustering | segment-ology

  6. Pingback: Match Cluster Report 1 | segment-ology

  7. Pingback: The Fundamental Building Blocks of Genetic Genealogy | segment-ology

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.