Different Y-DNA results from different companies?

August 17, 2014 Josiah Schmidt Tidbits

Did you get slightly different Y-STR values in your Y-DNA test results, if you took the test from two different companies? Fear not.

This happened to me when I took Ancestry.com’s 46-marker Y-DNA test (which is no longer for sale) and then a year later, took FamilyTreeDNA.com’s 37-marker Y-DNA test.

Now, the two Y-DNA tests examined most of the same markers. There were a few markers that Ancestry examined, which FTDNA did not. There were also a few markers that FTDNA examined, which Ancestry did not. These were not the markers that worried me.

When I got my FamilyTreeDNA Y-DNA test results back, I had no matches in their database at any level. Not a single DNA match, even at the 12-marker level. This surprised me, because I had had dozens of matches in Ancestry.com’s (now defunct) Y-DNA database, and the whole reason I had purchased the FTDNA Y-DNA test kit was to try to find more matches who might be located in a different database.

This caused me to ponder if it was ever possible for someone in a laboratory to accidentally enter in a wrong value. Has such a thing ever happened, and might it have happened to me? Might this be why I did not have one single Y-DNA match, anywhere in the entire FTDNA database?

I started comparing the Y-STR values that Ancestry.com had given for me with the ones that FTDNA had given to me. Everything was matching up fine until the last handful of markers.

DYS442 from FTDNA

FamilyTreeDNA result

Lo and behold, Ancestry.com had told me I had a value of “17” in my DYS442 marker and a value of “13” in my Y-GATA-H4 marker, while FTDNA told me I had a value of “12” in my DYS442 marker and a value of “12” in my Y-GATA-H4 marker.

Ancestry.com result

Ancestry.com result

Either some lab technician had made some serious typos when entering my results (could they really beĀ that sloppy?) or my genes had mutated between the time I took Ancestry’s test and the time I took FTDNA’s test (I knew my town’s drinking water was bad, but seriously Emmetsburg?).

Well, with some sleuthing around, I discovered that Ancestry.com used to have a notice posted on their website (they don’t seem to, anymore) stating that they utilized a different scale for counting markers than other Y-DNA testing companies do.

Specifically, Ancestry.com’s Y-DNA tests always showed DYS442 values as 5 steps higher than FamilyTreeDNA’s DYS442 values; Ancestry showed Y-GATA-H4 values as 1 step higher than FamilyTreeDNA’s Y-GATA-H4 values; Ancestry showed DYS441 values as 1 step higher than FamilyTreeDNA’s DYS441 values; and Ancestry showed Y-GATA-A10 values as 2 steps higher than FamilyTreeDNA’s Y-GATA-A10 values.

If you notice that your Y-DNA test results are slightly different on some markers according to different companies, don’t freak out. It may just be that the two different companies use different counting methods. Be careful when you get Y-DNA test results from one company and then manually enter them into a database on another company’s website. That other company may use a different counting method, and your Y-DNA results may be incorrect on that site. When in doubt, contact a company representative directly and ask them if there are any counting differences between them and the other company you used.

Furthermore, don’t freak out if you take a DNA test and don’t have a single match in the database. DNA is still a very new field, and relatively few people are in these databases yet. Also, yes, there are some of us with particularly rare DNA, and that doesn’t (necessarily) mean you’re some sort of mutant or were secretly adopted from Azerbaijan.

Now, if you take two Y-DNA tests from two different companies and every one of your Y-STR values are off by 7 steps, there might be a case for a severe mix-up at the laboratory, or you might need to move out from underneath the power lines.

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One Response to “Different Y-DNA results from different companies?”

  • Joel says:

    Thanks, as administrator of a small surname project, I found this very helpful. Some of the project members had old Ancestry results. I didn’t realize that different companies counted differently.


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