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GKBopp
DNA Project Notes

 

DYS 464 - Notes
Revised 14 September 2005

DYS 464 is a highly polymorphic (rapidly changing) marker. For most participants, DYS 464 is replicated 4 times and reported as DYS 464 a b c d. However, according to FTDNA, about 1.5% have one or more additional copies (reported as DYS 464 e f g).

"DYS 464 was discovered at the University of Arizona by Dr. Alan Redd. This highly volatile (fast mutating) marker is included in the panel to help show changes even within family groups that are closely related. DYS 464 is replicated 4 times in 98.5% of people from Europe and the Middle East (the balance having 5 or 6 copies). Because the markerís location on the Y-Chromosome is not determinable we sort the marker from smallest to largest (385a/b is treated the same way), and therefore it is possible to overstate or understate the actual genetic distance when making a comparison by eye."
http://www.familytreedna.com/ftGroupQIGuide.html

For examples of the genetic distance calculation for these markers, see Genetic Distance - FTDNA Calculation.
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John F. Chandler's explanation of how this happens:
"Just as the STR markers occasionally mutate by making an extra copy of
the short repeating sequence or dropping a copy, the DNA can make
copying errors on a huge scale by duplicating a long sequence or
dropping one. We know that this sort of error is especially likely for
DYS464 because it has happened three times already (which is why there
are normally four copies of DYS464, labeled a-d). You can think of the
copying process as a highly skilled typist copying a manuscript of
gibberish (coded text). Errors are rare, but not impossible. For
really big errors, imagine somebody opens a window, and the breeze sends
a few pages flying -- when they are retrieved, a page from the "done"
pile might end up on the "to do" pile or vice versa."

http://archiver.rootsweb.com/th/read/GENEALOGY-DNA/2003-03/1048268340
[edited; e.g., emails removed]
 
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Skim the DYS 464e column at the Walker project for examples. Note that not all persons in a family group have that marker.
http://freepages.genealogy.rootsweb.com/~fabercove/test_results.htm
 

 

GKBopp
DNA Project Notes
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