Exact match X DNA

[mudgeeclarke]

Hi,

I’ve never had an exact match X DNA result before yesterday.

I understand the broad facts but I’m lost as to what this means for two males with exact matching X DNA. I presume that it has arrived to both of us from our respective maternal ancestry. And in our case, the DNA notation states we have one identical common match. What should we be doing now to find how far back this match may have materialized with a common relative.

Thanks,

Colin

[jyb]

Dear Sir,

Can you please explain what you call "exact match X DNA result" and give an example?

Yes, it may mean that 2 males have a common ancestor if they have an X chromosome match. But we must consider the size of the segment and the number of SNPs in order to have a better insight of the relevance of the relationship.

[mudgeeclarke]

Thank you for your reply. As you can see, the length and number of cM for Chromosome 23 are noted by Geneanet. But there are no segments 1-22.

I am curious if this is sufficient to indicate how far back into our ancestries, the X Chromosome was with a common relative. It seems that this amount is quite small.

What is considered a “good” amount to work with in finding MRCA.

Thank you.

[jyb]

Dear Sir,

Theoretically 2 males can't have a full-identical segment on their X chromosome because they each have only one copy. Except that some DNA testing companies include duplicate data for the X chromosome in their raw file when there is really only one. Since our algorithm is gender-neutral, we interpret the data as it is.

Given the size of the segment and the low number of SNPs, it is not necessary to pay attention.

You can add a note to this match and come back to it later.

[mudgeeclarke]

Dear Sir,

Thank you for your reply. It is as I expected.

As I am a new arrival at Geneanet, I did not know that your posts were gender neutral and for males with X Matching, a more general description was employed, and was not specific .

Perhaps your small ‘comment box’ which appears should also note the reality as you have written now in your reply. ?

Best regards,

Colin Clarke

[jyb]

Dear Sir,

I'll forward your suggestion to the technicians.