No announcement yet.

What is CODIS?

  • Filter
  • Time
  • Show
Clear All
new posts

  • What is CODIS?

    I'm probably being really thick here, but what does CODIS mean with regards to ethnicity testing and why is it better?

  • #2
    The only CODIS with which I'm familiar is the FBI's Combined DNA Index System.

    It is a criminal database that is not used commercially for any purpose, including ethnicity testing.


    • #3
      Someone mentioned it in regards to the DNA tribes test?


      • #4
        Yes, CODIS, is the Combined DNA Index System. DNATribes uses the same 13 markers as CODIS and even uses the population databases assembled for law enforcement/forensic purposes.

        Because the population databases are of specific populations (the Szekler of Romania or Hispanics of California, e.g.) when your results are matched they are matched to specific populations. That is an improvement over what has been available herertofore - DNAPrint AncestryByDNA 2.5 - that only matches your to generic populations - European, East Asians, Native American, Sub-Saharan African. However, unlike DNAp's ABDNA, DNATribes does is not an admixture test and cannot give you (as DNAP's ABDNA does) estimates of generic ancestries by percentages.



        • #5
          Originally posted by tomcat
          DNATribes uses the same 13 markers as CODIS and even uses the population databases assembled for law enforcement/forensic purposes.
          I believe that the first part of this statement is true, but I doubt the second part.

          While DNATribes uses the same 13 markers as the FBI, I have never seen DNATribes claim to have access to the FBI database.

          If you are aware of such a claim, could you share a reference?


          • #6
            There's something i find puzzling about the DNA tribes match to population databases. Perhaps Tom or others know more about it.

            Since there isn't any attempt to tell which alleleles (from those 13 markers) you have come from your mother and which from your father, your own DNA is obviously a blend. Suppose your mother and father come from 2 very different ancestral backrounds and you know what they are. To pick 2 at near random (I hope), say your mother is Sweedish and your father is Chinese. Since you're a mix of the two, you may well get matched to a very odd population. That is, perhaps you most resemble genetically some group in location x that, based on very early migration patterns, has a blend of what now we now know as sweedish and now know as chinese. Yet your own mother and father's ancestors may never have set foot in location x. (True, you may look like folk there, should you decide to visit, which may be what some are interested in).

            Do others who know a fair amount concur with this? If you know it's wrong, let me know what's incorrect about the argument. the basic issue is one of matching blended DNA to populations. (the matching is more sensible if both parents have similar origins, or if there's some attempt to figure out which allele came from who- which is possible with programs that make some assumptions). Because of above issue, its hard to know what to make of any popultion matches to ones 13 marker test.


            • #7
              I’m not an expert or anything but I know that if one parent is Swedish and one parent is Chinese, you would get matches with Swedish and matches with Chinese. It’s not about matching you with people who are the same mix as you (Chinese-Swedish). Your results would explain where your matches live, like some of the Chinese might live in China and some in the U.S. or wherever else. It would say Chinese (Canada) or Chinese (Brazil). It’s the same for your Swedish matches. In addition, your strongest DNA is what shows up in the test. If you have an ancestor from way back that was Russian, you probably won’t get a strong Russian match or any at all even though it’s in your background.


              • #8

                Anyone with a computer may access the FBI CODIS database, and the Canadian equivalent, and a couple more that have other orientations.

                If you Google CODIS you will get numerous hits to population frequency papers for the CODIS markers or their equivalent, many of which have been incorporated into DNAT's database. That is the "cool thing" about this test - that it mines databases created for other purposes for genealogical use.

                Here's a forward from another list - "For those interested, the keywords PowerPlex and/or AmpFlSTR pull up many of the autosomal DNA studies that are indexed at ."

                (PowerPlex and Amp FISTR are brand names for CODIS sequencing products).


                Haplogroupc is correct - you would be matched to both Swedish and Chinese populations, not "strongly" but possibly "equally," and to a hypothetical blended Swedish-Chinese population more definitely.

                If one had a Swedish mother and a Chinese father (or parents of distinctly different genetics) one might be able to parse allele results, attributing one set to each and then research those results individually to derive more detail on each parent's origin.

                I don't know how DNATribes does their arithmetic, but there is some evidence that they sort by subsets of markers rather than the overall marker profile. I elected for the Basic test that returned results on eight/sixteen markers sorted over two population types - Tribal and Global. If I were to Upgrade, four/eight more markers would be reported to give matches to Continental populations.

                The thirteenth/twenty-sixth marker simply indicates gender. All markers are bi-allelic and have two values, the thirteen marker CODIS test returns 26 values.



                • #9
                  Originally posted by tomcat
                  Anyone with a computer may access the FBI CODIS database, and the Canadian equivalent, and a couple more that have other orientations.
                  Sorry, but that this is just not true.

                  It is imporant to distinguish between the 13 autosomal STRs that are used by CODIS and the database itself.

                  The 13 alleles are commonly used in population studies, but the FBI CODIS database is NOT used for anything other than law enforcement purposes as specified in 42 U.S.C. Chapter 136, Subchapter IX.



                  • #10
                    I must admit that has got me confused too. My mother is going to be 50% Northern European. Her mother's ancestors came from England, fact.
                    All I want is something that suggests my Grandfathers ethnicity, in a user friendly nice pretty graph or something to that effect-that he's made up of this bit and this bit.
                    How can the DNATribes test show that for example, my mother would be 50% Nothern European, then say 35% southern European/15% NA? Surely it would just say she is 85% European?
                    Can either of these tests say "yes he probably was from here and here"
                    I'm not bothered about different tribes at the moment, I just want to know roughly where 25% of my genes came from!!!!


                    • #11
                      The Ancestry By DNA test is the one that tells you the percentages. The DNA Tribes does a similar thing under their Continent Match but it’s not a percentage. It tells you how likely you are to belong to that group.

                      Unfortunately, neither test is that simple. Just because your mom is half English doesn't mean she is going to get 50 percent European on a DNA test from that side of the family because DNA is inherited randomly. Even though she is 50 percent by birth, she may have gotten 60 or 70 or even 40 percent European DNA. What makes things more complicated is that some people who are European get small percentages of Native American or East Asian or even Sub-Saharan African on their Ancestry By DNA test. That’s why a lot of people don’t trust the test. If your mom’s test reveals a small percentage of any one of those categories it won’t automatically mean she got them from her father.


                      • #12

                        See also Burrits OmniPop spreadsheet.


                        • #13
                          Originally posted by tomcat

                          See also Burrits OmniPop spreadsheet.
                          The link is interesting, but the mtDNA database and software program it references do not use data from the FBI CODIS database data.

                          The referenced database is drawn primarily from published scientific literature, with some forensic data from the Armed Forces DNA Identification Laboratory and the Illinois State Police.


                          • #14
                            Thanks to those who clarified- itwas helpful. So if both parents were sweedish, the match to sweeden might be high, and if one parent is sweedish might be say medium. ANd it's possible they do some sort of attempt ot cluster alleles that go together based on what you've suggested.

                            How come you chose dna tribes to do the test? was it because you liked the population stats they had for comparison? (as opposed to other companies? lots of genetic testing companies now offer the "identity test" that uses the same markers used in CODIS).


                            • #15
                              The other companies that I've seen don't offer detailed information on European ancestry for people who are mostly Native American. I have a relative who got 65 percent Native American on the Ancestry By DNA test. The rest was European. She wasn’t allowed to take the Euro Test because of the high Native American DNA so she couldn’t find out what her European ancestry was. But DNA Tribes matched her up with specific European groups as well as specific Native American groups. Plus, it only took 9 days to get her results because she paid the extra 25 dollars. I plan to take the test myself to find out my own European ancestry.