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Old 24th February 2018, 10:58 AM
Werinkme Werinkme is offline
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Join Date: Feb 2018
Posts: 2
Dna match is a X-match in the list but not in Chromosome browser?

Hello, can anybody help me with this? I have several X-matches in my list of dna matches, who don't show up as X-match when I compare them in the chromosome browser (on the ""X"" there is no color that belongs to that person).
Does anybody know how I should interpret this? Is it a real X-match or not? Thanks, Liesbeth
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Old 24th February 2018, 01:05 PM
KATM KATM is online now
mtDNA: K1a3 | Y-DNA: R-L1308*
Join Date: Nov 2012
Location: Mid-Atlantic coast, U.S.A.
Posts: 977
The X segments for these matches of yours are probably too small to be "real"; in other words, they are not IBD (Inherited by Descent).

You may be viewing the match in the Chromosome Browser using the default setting of 5 cM. You can change that setting (a drop menu above the selected names of the matches you are comparing) to show a smaller cM comparison (1+ or 3+ cM). The matching X segment should show at 1+ cM setting.

Although FTDNA marks matches as being an "X-match," almost always it is too small in size to be inherited. The current advice is that an X segment probably needs to be at least 15 cM, if not 20 cM, to really indicate a connection; in other words, matching X segments need to be about two times the size that a similar autosomal segment would be (7 to 10 cM minimum), to be worth investigating.

Last edited by KATM; 24th February 2018 at 05:25 PM. Reason: changed "usual" to "current" in second sentence of last paragraph
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Old 24th February 2018, 02:27 PM
John McCoy John McCoy is offline
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Join Date: Nov 2013
Posts: 588
Also, I think X matches should be disregarded if they are not also an autosomal match. Even if you somehow managed to get the same piece of an X chromosome as someone else who is not also an autosomal match, you would have no way to work out where that X came from.
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Old 26th February 2018, 01:06 AM
Werinkme Werinkme is offline
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Join Date: Feb 2018
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Thank you both KATM and John McCoy for your answers. Yes I tried with other default setting (>1CM) and indeed they do appear now. Good to know that these small X-matches are probably not real and not very useful.
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