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  • STRs count

    Hello,

    Another question, if you don’t mind. This has to do with STR or Short Tandem Repeats.

    I understand that the number of STRs can vary from individual to individual and change over time according to their own rate of mutation. What I don’t have clearly in my mind is if STR numbers only change upwards, in other words, will a mutation in a haplotype STRs always be a higher count or can the STRs also decrease?

    Victor

  • #2
    Well, if I may be permitted to answer a question with a question (it's a genetic problem with me): Do STR numbers always increase or decrease by one per mutation, or can they increase or decrease by multiples? In other words, to go from 15 to 17 repeats of a sequence, are two mutations required or can this occur in a single step?

    Jeff Schweitzer

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    • #3
      Originally posted by Victor
      Hello,

      <snip>

      I understand that the number of STRs can vary from individual to individual and change over time according to their own rate of mutation. What I don’t have clearly in my mind is if STR numbers only change upwards, in other words, will a mutation in a haplotype STRs always be a higher count or can the STRs also decrease?
      Victor, I started answering this last night but my computer died; so I'll try again. STR mutations can go up or down. I've seen discussions of studies saying that there is an equal chance of up or down, or a slight bias to up, or that small numbers tend to go up and large numbers go down. But they definitely go up and down.

      Bill

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      • #4
        Originally posted by dentate
        Well, if I may be permitted to answer a question with a question (it's a genetic problem with me): Do STR numbers always increase or decrease by one per mutation, or can they increase or decrease by multiples? In other words, to go from 15 to 17 repeats of a sequence, are two mutations required or can this occur in a single step?

        Jeff Schweitzer
        Jeff, in our project we have two three-step jumps in men who are fairly close cousins. One is a 11,11 in 385a and 385b, while the rest of that group are the normal R1b 11,14. In this case one triple-jump is far more likely than three one-steps. Another theory is that in his case 385b has been deleted and the technician only sees one peak in the results and assumes it's two 11's, while in fact it's one 11 and one nothing.

        The other one we have is in 464, which has four parts. We don't have any multiple-step jumps in markers that don't have two occurences. But that would not surprise me.

        Bill

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        • #5
          Originally posted by Bill Hurst
          Jeff, in our project we have two three-step jumps in men who are fairly close cousins. One is a 11,11 in 385a and 385b, while the rest of that group are the normal R1b 11,14. In this case one triple-jump is far more likely than three one-steps. Another theory is that in his case 385b has been deleted and the technician only sees one peak in the results and assumes it's two 11's, while in fact it's one 11 and one nothing.

          The other one we have is in 464, which has four parts. We don't have any multiple-step jumps in markers that don't have two occurences. But that would not surprise me.

          Bill

          ok how do i have trust anything like e3b1 or even just 16-18 is correct
          please try to understand what you wrote means nothing can be trusted ?
          tell me i am wrong

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          • #6
            Multiple jumps

            Thanks for your answers. This is so interesting.

            About multiple step jumps, Bill, like the close cousins you mention with the 11 vs. 14 STRs @ 385b, are you aware of somebody else that has a similar occurrence?

            What are the odds that it could it be a lab misreading?

            Victor

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            • #7
              Originally posted by Jim Denning
              ok how do i have trust anything like e3b1 or even just 16-18 is correct
              please try to understand what you wrote means nothing can be trusted ?
              tell me i am wrong
              Jim, I wish I could tell you that you're wrong but I can't. I feel like there's still a lot of uncertainty when it comes to the interpretation of all these new genetic findings.

              All the new scientific methods that allow us to identify and quantify the elements of our chromosomes are really amazing and outstanding. But there's still much speculation and conjecture about the true significance of it all. Even so, I don't see any reason to despair. It is just a matter of patience and soon enough we'll have some breakthrough.

              Victor

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              • #8
                Originally posted by Victor
                Jim, I wish I could tell you that you're wrong but I can't. I feel like there's still a lot of uncertainty when it comes to the interpretation of all these new genetic findings.

                All the new scientific methods that allow us to identify and quantify the elements of our chromosomes are really amazing and outstanding. But there's still much speculation and conjecture about the true significance of it all. Even so, I don't see any reason to despair. It is just a matter of patience and soon enough we'll have some breakthrough.

                Victor

                i personally think acknowledgeing that fact is good
                yeah it could be neolitic in which case i might be ice mans gggggnephew or i could be the ggggggnephew os a shephardic jew like in ivanhoe maybe from rebecca's brother all thats great and a target .i just dont like being limitd to 30,000 years ago

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