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  • DYS464

    Having trouble calculating/understanding the Genetic distance of this marker:

    A-15,15,15,15
    B-15,15,17,18

    These two individuals hade the following results. I see the Genetic distance of 5 but after reading but not understanding several articles on this there seems to be a special rule? HELP!!!!

  • #2
    According to this article, you use the infinite alleles method on multi-copy (palidromic) STRs such as 464. https://www.familytreedna.com/learn/...romic-markers/ Under this method, you add 1 for copy changes (ie if they have adifferent number of hypenated numbers) and another 1 (for a max of 2) if there are any differences in the values of the numbers (regardless of how many or by how much). Using this method, in your case, there are no copy number changes, so the genetic distance based on this STR should be 1.

    However, last year, FTDNA game out with some revisions. See https://dna-explained.com/2016/07/27...etic-distance/ According to the method described in this article, you add 1 for any copy changes as before. However, now for differences in values, what you are supposed to do is eliminate all pairs of matching values (in your case, the 15s) and then add 1 for each remaining pair of values that are different. In your case, there are 2 pairs of values that are different, so the genetic distance would be 2.

    Personally, I find the article on the new changes rather unclear because (i) it suggests that step-wise calculations were previously used on each value in a multi-copy STR, which is inconsistent with the article on the infinite allele model, and (ii) it states that the changes will always result in more matches rather than fewer, but that is not true if we assume that the infinite allele method was previously used because under that method the maximum distance added would be 2 but under the new method , the max added for 464 would be 5 (1 for differences in values in each of the 4 numbers and 1 for a change in the number of copies).

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