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  • Genetic Distance vs Steps

    I am a little new to the terminology here and a bit confused. What is the difference between genetic distance and steps.

    When I do a matches search I have no matches at one step of 12 markers, but when I go into Haplogroup origins I have heaps of people with a genetic distance of one in the same 12 markers. How does that work.

  • #2
    I could be wrong but I believe that steps and genetic distance are the same thing .
    I have always been confused over the same issue.
    We get matched ( or not matched ) with people who use this site for DNA testing . Haplogroup origins is a database populated by other testing sites and and is being used as reference. So they are not avaiable for contacting.
    My belief is this is the difference , but not 100% sure.

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    • #3
      Originally posted by Brunetmj View Post
      Haplogroup origins is a database populated by other testing sites and and is being used as reference.
      To clarify this...

      Haplogroup Origins & Ancestral Origins do include samples from certain scientific/academic studies in addition to FTDNA customers. However, they do not include data from other commercial testing companies.

      To answer the original question...

      GD & Steps is the same thing. FTDNA primarily shows only exact 12/12 matches on your Matches page. The only exception is 1-step (11/12) matches who are in the same project(s) as you will be shown as well. Any 1-step matches who are not in the same project as you will not be shown.

      On the other hand, the Haplogroup Origins & Ancestral Origins pages show 1-step matches from the entire database.

      So you may very well see more matches on the Origins pages than you see on your Matches page.

      Elise

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      • #4
        So you may very well see more matches on the Origins pages than you see on your Matches page.
        I don't want to hijack the op's thread but I think this question relates to it.
        Are those matches portrayed in haplogroup origins pages real people that can be contacted? Or are they part of a larger anonymous database somewhere in cyber space?

        Comment


        • #5
          Originally posted by Lassie View Post
          I am a little new to the terminology here and a bit confused. What is the difference between genetic distance and steps.

          When I do a matches search I have no matches at one step of 12 markers, but when I go into Haplogroup origins I have heaps of people with a genetic distance of one in the same 12 markers. How does that work.
          In my understanding a step is the difference at one particular marker to another match.

          Genetic Distance is the total number of differences(Steps, mutations) between each match

          If you dont see matches on match page that show in Haplogroup Origins it could be your settings. Make sure Show matches for Entire Database is selected on match page

          Matches on Haplogroup Origins page may also list the users that have chosen to not make their results public...
          Last edited by prairielad; 22 May 2012, 03:11 PM. Reason: added

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          • #6
            Oh I see thanks for clarifying steps from genetic difference.
            I know my settings are set against the entire database
            Because I have no exact matches at any marker level and only 9 1step matches at 12 with nothing close above 12 marker it has always been hard for me to understand these matches at different locations of the site.

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            • #7
              Genetic Distance faq id: 701

              There are two meanings of Genetic Distance.

              Genetic Distance is the number of differences, or mutations, between two sets of results. A genetic distance of zero means there are no differences in the results being compared against one another, i.e., an exact match. This is the meaning when comparing Y-chromosome DNA or mitochondrial DNA.
              For autosomal DNA comparisons, genetic distance may refer to the size of a DNA segment. The genetic distance is then the length of the segment in centiMorgans.

              What is a one-step mutation, two-step mutation, etc.? faq id: 914

              When comparing the results of Y-chromosome STR (short tandem repeat) tests, the difference between the two values at a marker is the number of steps. That is, a one-step mutation means that the count for a single STR has changed by one. A two-step mutation means that the count for a single STR has changed by two.

              For example, when comparing kit B193 and kit B173, the STR marker DYS393 has changed from 13 to 12. The difference between 13 and 12 is 1 {13-12= 1.}. This is considered a single or one-step mutation.

              In this example, kit B193 has a DYS391 value of 10 and kit B132's value is 8. The difference between 10 and 8 is 2 {10-8= 2.}. This is then considered a two-step mutation.

              When you have a question go to Learn more in the subject of interest Y-DNA, mtDNA, or Family Finder. Its at the top of the box.

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              • #8
                example of steps vs gd

                faq id 914 & 915 does explain it somewhat but I don't think the example clears up the confusion.

                If B193 and B173 had a step of 2 at DYS393 then would that be a genetic distance of 2. Right?

                Genetic distance sample does not give and example of more than one step.
                If, B291 was 27 at DYS389 and B125 was 30 at DYS389 then this would be a 3 step so I assume a GD =3?

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                • #9
                  In regards to 1 Step or 2 Step, believe this refers to the mutation that occur in an individuals line from their ancestor. Whether the value change by 1 (from parent to offspring)which is referred to as a 1 Step Mutation or the value change by 2 which is referred to as a two step mutation.

                  Mutations are usually a 1 Step mutation. 2 Step or more are rarer therefore
                  unless you can date the mutation with in your line and determine if it was a 1 step or 2 step mutation each step is automatically assigned a genetic distance of 1, and a 2 step will be assumed to be two separate 1 Step mutations and assigned a Genetic Distance of 2

                  If your results differ at one marker then another match by 3 it is not referred to as a 3 step mutation. In regards to testing (having to do with mutation rates) it is assumed that there was 3 separate 1 step mutations.

                  I will use my line as an example, which has a presumed 2 step mutation on one of the markers as well as another 1 Step mutation on another marker that happened in my father or my grandfather. Will Need to test an uncle to determine if 2 step mutation is a 2 step or if value had a 1 step mutation in Grandfather and then same marker had another 1 step mutation in my father.
                  My fathers first cousin has a separate 1 Step mutation at another marker.
                  Both Cousin tested to 67 markers
                  Total Genetic Distance between First Cousin = 4
                  Last edited by prairielad; 23 May 2012, 02:08 AM.

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                  • #10
                    steps vs genetic distance

                    I suppose a mutation at the same position would be unlikely. So I see how a 2 or more step may be only one mutation and therefor 1 gd.

                    Also I did not know about the Haplogroup and Ancestral origins coming from other companies. So that clears that up.
                    Thanks guys

                    Comment


                    • #11
                      Originally posted by Lassie View Post
                      Also I did not know about the Haplogroup and Ancestral origins coming from other companies. So that clears that up.
                      They don't come from other companies. Please re-read what I posted above.

                      Elise

                      Comment


                      • #12
                        They are both the same thing

                        Originally posted by Lassie View Post
                        I suppose a mutation at the same position would be unlikely. So I see how a 2 or more step may be only one mutation and therefor 1 gd.

                        Also I did not know about the Haplogroup and Ancestral origins coming from other companies. So that clears that up.
                        Thanks guys
                        I can't find where I originally read this but I'm going to see if I can find it anyway but for now this will have to do. This is pretty much what it was saying. If sample "A" says marker 391 is 10 and sample "B" is 11 that's a Genetic Distance of 1. But if sample "A" says marker 391 is a 10 and sample "B" is 12 than that's a Genetic Distance of 2. You count each difference as a single GD even if its on one marker. If you miss on other markers you count them as single GD giving you your total.

                        Its the same way with steps every difference is counted as a single step even if it appears on the same marker. Count the differences gives you the number of steps.
                        Last edited by EdwardRHill; 23 May 2012, 10:45 AM.

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                        • #13
                          Are we certain that mutations take place at a consistent rate across the whole Y chromosome though? I have no close matches but if I look at my closest matches (12+ to 15 or so GD at 67 markers) they there are many markers where everyone is the same while the differences seem to cluster amoungst a much smaller set of markers.

                          That is a small data set but it implies to me that mutations do not happen at a consistent rate across the Y which would mean that different markers would have different levels of significance in terms of figuring out how far back the common ancestor most likely was.

                          Does that make sense or am I totally lost?

                          Comment


                          • #14
                            Originally posted by 1_mke View Post
                            Are we certain that mutations take place at a consistent rate across the whole Y chromosome though? I have no close matches but if I look at my closest matches (12+ to 15 or so GD at 67 markers) they there are many markers where everyone is the same while the differences seem to cluster amoungst a much smaller set of markers.

                            That is a small data set but it implies to me that mutations do not happen at a consistent rate across the Y which would mean that different markers would have different levels of significance in terms of figuring out how far back the common ancestor most likely was.

                            Does that make sense or am I totally lost?
                            Yes different rates for different markers. I would not wast time wondering about your 12 to 15 missed matches. Some explanation for 67 marker test below.

                            8-9 Only Possibly Related

                            58-59/67 You share the same surname (or a variant) with another male and you mismatch by eight or nine ‘points’. It is most likely that you did not match 24-25/25 or 35-37/37 in previous Y-DNA tests. If several or many generations have passed it is possible that you are related through other family members. The only way to confirm or deny is to test additional family lines and find where the mutation took place. Only by testing additional family members can you find the person in between each of you...this 'in betweener' becomes essential for you to find, and without him only the possibility of a match exists, but further evidence should be pursued. If you test additional individuals you must find the person whose DNA results falls in-between the persons that are 8 or 9 apart demonstrating relatedness within this family cluster or haplotype.

                            10-11 Not Related

                            56-57/67 is too far off to be considered related, unless you can find an “in-betweener’ as for determining ‘Only Possibly Related,’ above. It is important to determine what set of results most typifies the largest number members of the group you are 'close' to matching. You may be 57/67 with an individual, but 61/67 with the center of the group, and your potential relatedness to him is through the center of the group.

                            >11 Not Related

                            55/67 You are not related and the odds greatly favor that you have not shared a common male ancestor with this person within thousands of years

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                            • #15
                              But isn't that somewhat contradictory? It's saying that if you have >N differences you are not related but the real question should be how common are the mutations involved?

                              Maybe the implication is that even in the best case scenario (Markers that mutate frequently) that kind of difference is to large to show a likely relationship within the past thousand years.

                              Comment

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