Can someone set me straight?

[sarahmj]

Hi all,

So I've noticed some things about the X chromosome that I don't quite understand...

FYI, I am female and have had both my parents' DNA tested also. It's very easy to know which DNA match, matches which side of the family, especially because my Mum is Maltese/Italian.
I have a DNA match who my Dad and I share, I share about 45 cm and my Dad 46 cm with this woman. But she also matches me on my X chromosome, but not my Dad's. I don't understand why she would match me on the X and not my Dad? What is the threshold for a significant match on the X?
Because we have common X DNA, I have assumed she matches me somewhere on my Dad's mother's side...am I safe in that assumption?

Also on Gedmatch, I have noticed that I have a lot of X chromosome matches, but many share no autosomal DNA. What is the significance of this? Is it because the X goes through less recombination than the other chromosomes?

Thanks for your help!

[grahcom]

While I may not be answering your Q's, There is a thread on the X at this site that maybe of some interest to you. https://www.facebook.com/groups/dnanewbie/ it also has a link to http://www.thegeneticgenealogist.com...-x-chromosome/

[prairielad]

Hi all,

So I've noticed some things about the X chromosome that I don't quite understand...

FYI, I am female and have had both my parents' DNA tested also. It's very easy to know which DNA match, matches which side of the family, especially because my Mum is Maltese/Italian.
I have a DNA match who my Dad and I share, I share about 45 cm and my Dad 46 cm with this woman. But she also matches me on my X chromosome, but not my Dad's. I don't understand why she would match me on the X and not my Dad? What is the threshold for a significant match on the X?
Because we have common X DNA, I have assumed she matches me somewhere on my Dad's mother's side...am I safe in that assumption?

Also on Gedmatch, I have noticed that I have a lot of X chromosome matches, but many share no autosomal DNA. What is the significance of this? Is it because the X goes through less recombination than the other chromosomes?

Thanks for your help!

What size is this X match?
You have 2 X's, while your father only has one. If this X match is small, it could be a false segment due to algorithm picking values from both your X's to create a IBS segment.