No result for DYS 439

[JSW]

In my Adams group I have a result with one maker with a foot note
"System assigned value. Your DNA sample produced no result for DYS 439."

The system assigned the AMH modal value - which might be right as the Haplogroup is estimated as R1b.
However it IS just a guess.
Is this man's Y-DNA likley to be so unique that all his ancestors
and male descendants will also have no result for DYS 439?

IF SO then this one maker can be used as family maker as it is
really rare to not get a result.

On the other hand this could be just happenstance for this man
at this time and so we really just have DYS 439 as an untested marker.

My thinking is to report the value as X and not with AMH modal value.
Any Comments/Advice?

[dennis]

John:
I think your approach would be more appropriate than an assigned value. When comparing the results from the test with the missing value with others, you would then omit that locus from consideration in both haplotypes. It seems to me that using an assigned value could contribute to a false positive match.
Dennis West

[admin]

From Bennett Greenspan:

In about .25 of 1% of the samples that we have run, the person just doesn't have the marker DYS 439. We have a specific family that has had 3 people test and none of them (all the same surname) have a value for 439...this after a collective 9 test runs on the 3 samples. Whereas the lab runs markers not by the person, they did ask me last time when this marker failed :"is this another of those XYZ family samples...all other markers matched otherwise."

Because this represents a deletion it is significant genealogically...it just doesn't happen very often. The way the algorithm works is it compares the other 11 markers of the first panel of 12 to each sample that is most closely connected, match wise, and supplies the value that is most like the nearest complete samples, so in theory the value could be a 10 or 11, and not just a 12.