Re: Determining Ancestral Haplotypes - recLOH
-
In reply to:
Re: Determining Ancestral Haplotypes - recLOH
Emily Aulicino 4/16/07
It is important for a project coordinator to be aware of the possibility, since a recLOH can lead to incorrect conclusions about the relatedness of two people. Several projects, including ours, have encountered them.
The result of a recLOH is the loss of one value (allele) and doubling of another on a multicopy marker. A section containing one copy of the marker is deleted, but recreated from another segment containing the other copy. This occurs in areas of DNA where it bends back on itself so the two sections involved are close to one another.
For example, 3 members of a family might match on 25 markers except DYS385. Two might have values of 11 and 14, while the other, 11 for both. He would be a genetic distance of 3 from the other two and the guidelines would suggest that he was probably not related:
http://www.ftdna.com/GDRules_25.htmlhttp://www.ftdna.com/GDRules_25.html
However, since there is a another more likely mechanism requiring only a single step, we would reduce the genetic distance to 1.
It becomes especially important when multi-copy markers are near one another. Several may undergo a recLOH at once and the results may look like a total mismatch at first.
More Replies:
-
Map of Palindromic Region
Robert Stafford 6/25/07
-
Re: Determining Ancestral Haplotypes - recLOH
Robert Stafford 5/20/07
-
Re: Determining Ancestral Haplotypes - recLOH
Robert Stafford 4/17/07