Genetic testing on yours truly

Posted by Preston G. on April 24, 2014 at 12:42 pm
Apr 242014

Well, the Garrison DNA (mine) has been analyzed. I described my testing as it went along at the Garrisons of Georgia site, but there’s very little activity there these days. Since this is the “newspaper of record” for our branch of Garrisons, I thought I should give a summary here.

I first did National Geographic’s Geno 2 test (which was on sale for $40 less than usual.) This a chip-based test which measures the state of each of ~150,000 single nucleotide variants. About 12,000 are on the Y chromosome (inherited from your father if you are male,) a few thousand on the mitochondrial DNA (inherited by males and females from your mother only,) and the rest on chromosomes 1-22 (autosomes) (which you get from both your parents.) In any single person only a small fraction of markers will be positive (“derived” as opposed to “ancestral,”) since the markers on the chip were chosen to be able to test people all over the world (and chosen so as have no markers with known medical or trait-causing effects.)

My mito DNA is type H4a1a4a. The H haplogroup is very common in Europe. One of its subtypes, H4, is not terribly common and occurs scattered around Europe and the near east. The prevalence (%) of H4a1a4a isn’t known, but it would be pretty low. That came from my mom Sue Foster Garrison, and so is not very relevant for other Garrisons beyond my brothers.

My Y DNA is haplogroup R1b-Z331*. This should apply to all male Georgia Garrisons (unless there has been one of those “non-paternity” events where a foreign Y has snuck in.) The designation means that we have a single nucleotide variant called Z331, and it is downstream in time from R1b, the most common major haplogroup in western Europe, accounting for about half the men there, and some large proportion in the U.S., Canada, Australia, etc. The * means that I tested negative for all the known markers downstream of Z331.

There are 2 big groups within R1b, P312 which makes up about 75% and U106, which is about a quarter. Z331 is a subgroup of U106 and seems to be ~0.5-1% of it. There may be very roughly 100,000 Z331* men in Europe today. U106 seems to have originated in northwest Germany about 4000 years ago (still being disputed.) I have joked on the U106 discussion group that Z331 seems to be the group where our ancestors really didn’t like each other and tried to get as far away as possible from each other. The location of the oldest known ancestor is only known for a few of us, but includes men in Holland, Germany, Spain, Romania, England, Scotland, Bulgaria and the east coast of India (almost certainly a Y from some colonialist.) The age of Z331 isn’t even estimated yet, but is probably 3000 years or so. Single nucleotide mutations occur about every 3-4 generations (in the part of the Y that can be most easily analyzed,) so there are ~20-30 mutations on our Y that occurred since Z331, and the eager beavers of the U106 group (and various scientific, forensic and commercial labs) are looking for them. I could find essentially all of them with the FT-DNA’s Big-Y, but at $750, the price tag seems too high.

The Genographic Project also gives results concerning what known populations you most resemble, based on your autosomal results. They don’t make very clear how they calculate these results, so it’s hard to tell what they mean. In any case, my autosomes look more like a German or Englishman than anyone else, not surprisingly, since most of the lines leading to me probably went through the British Isles, and almost everyone in the isles came from northwest Europeans over the last few thousand years. I was somewhat less close to a typical Romanian(!) or Greek. Oh, and I’m 2% Neandertal, so don’t mess with me.

So much for the bigger picture. If you want to find or verify a relation to someone in your extended family, where the common patrilineal ancestor was within the last few centuries, the main way to do that is by analyzing your Y-STRs (short tandem repeats,) in which a short sequence of 2-6 nucleotides is repeated a varying number of times (generally 8-40 or so.) There are hundreds of these STR loci on the Y, but the genetic genealogy companies have standard sets of 12-111 loci that they will test for a few hundred dollars. STRs change their copy number pretty frequently, usually by a step of 1. You get a series of numbers, each one representing how many copies are present at a particular STR locus.

No one descended from Isaiah Garrison (~1745~1790) had been tested, although a number of descendants of his brother Jedediah have been tested. So I coughed up the money and had 67 markers tested. No surprises. I differ by 3-6 STR shifts from other Garrisons, as well as known borrowers of our Y like the Sissons, Capps and McCubbins. So the wives of the Garrisons on our line have been quite faithful; the husbands, at uncertain distances in time or generations, have been less so. Remember, all your secrets will be known, and possibly before any divine judgment, if DNA analyzers get their way, (which is why private DNA testing is illegal for the moment in France. :) )

Preston G.

Retired biochemist. One of 16 grandchildren of Verne Garrison and Dorothy Logan Garrison.

2 Responses to “Genetic testing on yours truly”

  1. Dave,

    I sent you an e-mail with this material. Putting it here so it will be recorded on the blog.

    Nice to hear from a 1/100th or so cousin. :)

    It is a pretty small group. H4 is considerably less common than some of the other H subgroups. Last time I looked there were only about 5 or 6 H4a1a4as who had tested with Family Tree. The scientific papers don’t do geographic mapping at these fine levels of resolution (yet?) so it’s a matter of luck if your detailed type happens to match someone whose complete sequence or detailed haplotype is used in a paper. No doubt Genographic has some interesting data which they haven’t published yet. Maybe soon – they put a new Y tree up recently and told me that a new mito tree is in preparation.

    Mito SNPs only happen on average about every 2500 years, so even if you only differed from someone by one SNP there could be a lot of migration from the common ancestor. If I remember right they said H4a1a4a is only about 1 in 1000 testers. I think they have tested >150,000 on Geno 2, so they may have ~150 of us. Would be interesting to know where the European (or otherwise) roots of those people are. I would bet they are spread around in central-western Europe mostly. In one paper the highest frequency of H4 was in Poland at 5%.

    There is an open access paper on Hg H from 2013:

    I have been more focused on Y results and have neglected to get one review on my library trips that I think has some geographic results on H subgroups:

    Trends Genet. 2006 Jun;22(6):339-45. Epub 2006 May 4.
    Harvesting the fruit of the human mtDNA tree.
    Torroni A1, Achilli A, Macaulay V, Richards M, Bandelt HJ.
    Author information
    Human mitochondrial DNA (mtDNA) studies have entered a new phase since the blossoming of complete genome analyses. Sequencing complete mtDNAs is more expensive and more labour intensive than restriction analysis or simply sequencing the control region of the molecule. But the efforts are paying off, as the phylogenetic resolution of the mtDNA tree has been greatly improved, and, in turn, phylogeographic interpretations can be given correspondingly greater precision in terms of the timing and direction of human dispersals. Therefore, despite mtDNA being only a fraction of our total genome, the deciphering of its evolution is profoundly changing our perception about how modern humans spread across our planet. Here we illustrate the phylogeographic approach with two case studies: the initial dispersal out of Africa, and the colonization of Europe.
    Before long everyone’s mito DNA (and maybe whole genome) will be sequenced for medical reasons, and some fraction of those people will put their results into the databases. That may be what it takes to map these rare haplogroups.


    Preston G.

  2. Gooday Preston,
    I am posting from Australia after having found your interesting site. Like you, my mito DNA is type H4a1a4a, which, as you have said, is not too common. I have tried to find out where it originated and I was wondering if you have any idea. It would seem from what I have seen so far it is less uncommon amongst Basques.

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