Marleen Usually the X-chromosome is passed down as a recombination of the mother's 2 X-chromosomes but an X can be passed down intact in about 20 to 25 % of the births. X-inactivation or lyonization is still poorly understood but it was not my impression that the X was deactivated as an entire chromosome but as section of one or the other copies of the chromosome. X-based diseases would be affected by how the deactivation works. (Issues like hemophilia or color blindness) RPaine -----Original Message----- From: Marleen Van Horne Sent: Thursday, November 9, 2017 1:37 PM To: [email protected] Subject: [DNA] x Chromosome Question A woman gets one x chromosome from her father and one from her mother. "Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in cells other than egg cells. This phenomenon is called X-inactivation or lyonization. X-inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell. Because X-inactivation is random, in normal females the X chromosome inherited from the mother is active in some cells, and the X chromosome inherited from the father is active in other cells." When a woman conceives, is the x chromosome she passes to the child a complete copy of one or the other of the x chromosomes she inherited from her parents, or is it a mix and match version of her two x chromosomes? It might seem late in the game for me to be asking this question, but I have always found it confusing. Marleen Van Horne ------------------------------- To unsubscribe from the list, please send an email to [email protected] with the word 'unsubscribe' without the quotes in the subject and the body of the message

https://en.wikipedia.org/wiki/X-inactivation It seems that this is saying it's entirely inactive, along it's whole length -----Original Message----- From: Robert Paine <[email protected]> To: genealogy-dna <[email protected]> Sent: Thu, Nov 9, 2017 2:07 pm Subject: Re: [DNA] x Chromosome Question Marleen Usually the X-chromosome is passed down as a recombination of the mother's 2 X-chromosomes but an X can be passed down intact in about 20 to 25 % of the births. X-inactivation or lyonization is still poorly understood but it was not my impression that the X was deactivated as an entire chromosome but as section of one or the other copies of the chromosome. X-based diseases would be affected by how the deactivation works. (Issues like hemophilia or color blindness) RPaine -----Original Message----- From: Marleen Van Horne Sent: Thursday, November 9, 2017 1:37 PM To: [email protected] Subject: [DNA] x Chromosome Question A woman gets one x chromosome from her father and one from her mother. "Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in cells other than egg cells. This phenomenon is called X-inactivation or lyonization. X-inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell. Because X-inactivation is random, in normal females the X chromosome inherited from the mother is active in some cells, and the X chromosome inherited from the father is active in other cells." When a woman conceives, is the x chromosome she passes to the child a complete copy of one or the other of the x chromosomes she inherited from her parents, or is it a mix and match version of her two x chromosomes? It might seem late in the game for me to be asking this question, but I have always found it confusing. Marleen Van Horne ------------------------------- To unsubscribe from the list, please send an email to [email protected] with the word 'unsubscribe' without the quotes in the subject and the body of the message ------------------------------- To unsubscribe from the list, please send an email to [email protected] with the word 'unsubscribe' without the quotes in the subject and the body of the message

Thanks to all who replied to my x Chromosome question, now, about the other 22, so they get mixed and matched in a way similar to the x, so that there is only one functioning strand for each chromosome? The article was particularly helpful. I was aware of the x chromosome influence on IQ, but I did not talk about it , because my source did not have genetic expertise. I heard it on NPR's Car Talk, many years ago. Tom brought it up one Saturday morning. I have since then been amused by all the powerful men who marry arm candy, then wonder why their sons cannot find their way out of a wet paper bag. No offense intended to any one in particular. Marleen Van Horne