Anthrogenica > Human Population Genetics > X Chromosome (X-DNA) > New Ground for Me: The X Chromosome
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I must confess that I have totally neglected the x chromosome, but it sparked my interest yesterday when I discovered that a close Family Finder and Ancestry DNA match of mine (a female) matches my dad on the x chromosome.
Her great grandmother and my great grandmother were sisters, and this particular great grandmother of mine is my dad's maternal grandmother. So, evidently my dad's x chromosome came down via his maternal grandmother, as did his mtDNA, and this match got one of her x chromosomes via my great grandmother's sister. I think she should also be a mtDNA match for my dad, but she has not had an mtDNA test yet.
The maiden surname of these two ancestors is McElroy. Their mother's maiden surname was Nickelson.
I'm not sure what exactly can be done with the x chromosome, but now I have a reason for looking into it.
Bollox79
Do you know your maternal haplogroup? I found mine out per Geno 2.0 and had it transferred to FTDNA, but still have to test the coding regions etc. According to FTDNA haplogroup geographical origins for my haplogroup T2b2b - 3x as common in Ireland (17 kits) and 2nd in Scotand (8 kits I think) than anywhere else in the Isles and parts of Europe.
I plan on fully testing my mother to help sort my autosomal results, as I have recent Scots and Irish on both sides... so to sort them right now is pretty hard (though the ones from Canada most likely from my Mother's family from Ontario etc.).
There is a nifty male x-chromosome inheritance chart on the web... I filled it out for myself - was interesting to say the least:
Positions on the X-chromosome inheritance chart:
position 1: Me - Charlie!
Position 3: Susan O'Dwyer
Position 6: Philip O'Dwyer
Position 7: Lorraine Brownell
Position 13: Isabel McGuire (1885 New York)
Position 14: Francis Edward E Brownell (1897 New York)
Position 15: Alice Mae Wheeler (1898 New York)
Position 26: Alexander J. McGuire (1860 Trenton, Ontario)
" 27: Bridget Leavy/Dunleavy (1859 New York)
" 29: Annie Laurie Clark (1869 New York)
" 30: Frank A Wheeler (1856 New York)
" 31: Mary Colway (1862 New York)
" 53: Jane MacAulay (18 APR 1834 • Murray Township, Northumberland County, Ontario, Canada)
" 54: Robert Leavy/Dunleavy (1815 Ireland)
" 55: Margaret Leavy/Dunleavy (1819 Ireland)
" 58: La Fayette Clark (1822 New York - Clarks were probably Scots further back in time - possible connection to Clan Chattan and MacPherson per another relative's research and family tradition - many Clark men were clergy/parsons)
" 59: Charlotte Almy Shearman (1826 Rhode Island)
" 61: Delilah B. Wood (New York)
" 62: Martin Colway/Cowlay (1825 - probably Dorrah, Tipperary according to surname frequency/census records)
" 63: Bridget "Dana" Colway/Cowlay (abt 1843 Ireland - Dana recorded as a Gaelic forename/surname in SW Ireland - though possibly from Roscommon per census records)
" 106: Henry MacAulay (abt 1785 Ireland - possibly Antrim - posslby from Isle of Lewis/Hebrides per autosomal results such as 4th cousin Frasers living in Scotland (two of them) with roughly half their ancestry from Reef in Lewis - and the other half Western Highland ancestry? MacAulays were related to the MacDonalds most likely and married McGuires)
" 107: Margaret MacAulay (abt 1793 probably Northern Ireland)
" 109: Robert Leavy/Dunleavy's mother (? Ireland)
" 110: Margaret Leavy/Dunleavy's father (from Ireland)
" 111: Margaret Leavy/Dunleavy's mother (from Ireland)
" 117: Luranna Babcock (abt 1800 New York)
" 118: Richard Shearman Jr. (abt 1791 Portsmouth, Rhode Island)
" 119: Sarah Ann Rogers (abt 1799 Middletown, Rhode Island)
" 122: Delilah B. Wood's father (?)
" 123: Delilah B. Wood's mother (?)
" 125: Martin Cowlay's mother (Ireland)
" 126: Bridget Dana's father (Ireland)
" 127: Bridget Dana's mother (Ireland)
Yeah, I know my mtDNA haplogroup. It's there on the left below my screen name, avatar, etc.: U5a2c3a. That comes from BritainsDNA's Chromo2. I've only done HVR1 with FTDNA and got U5, although I may go for the FGS with them eventually, since the price has come way down on that over the years.
Thanks for the info. Amazing that you are able to trace the path of your x chromosome like that. I have not really started investigating it yet. I figured I could work on that a little this coming weekend when I have time.
I'm not sure how I will trace my dad's x chromosome back beyond his maternal grandmother, since I don't know from which parent she got that particular x and obviously have no opportunity to test her or her parents, who have all been dead a long time. I'll have to give it some thought.
Just looking at my own x matches very quickly (in about five minutes or less), I noticed that a woman who is an x match for my mom on her mom's side is not among them, which tells me the x she passed on to me she got from her father, unless I am mistaken, which is very possible, since I am in a hurry this morning and just took a quick look. Anyway, that's what it looks like, and it's kind of fun trying to figure it out.
Ahh yes your mtDNA was right there lol! If it was a snake it would have bit me in the arse!
Yeah I still have to do the testing with FTDNA - but at least Geno 2.0 gave me the haplogroup etc. As for my list of x-chromosome inheritance I got that here for a male to fill out. I just put names next to the position numbers etc... and there is another chart just like it, but it has the percentages there instead of the position numbers. 13774
I was happy to see that apparently my haplogroup does line up with my paper trail to Ireland. I still don't understand the x-chromo bit as much as I do the Y-DNA. That has been my main focus for the last few years. I have to test my father's mother who is still alive and she is 96 years old and tough as nails. One of her grandmothers (I think on her father's side from PA - PA Dutch and all that mixed with Irish) gave birth to a kid on the blanket in the house and then got up and fixed dinner!!! They made them tough back in the day. She is first on my list of testing, then my father's sister and of course my mother! We lost the old man in an accident at work, so I have to try and use his mother and sister to recreate his genome and my mother and my results of course... if that is possible? Something called phasing? Haven't gotten into that yet!
Good luck on your testing!!
As far as I can tell - and I am a complete and total rookie when it comes to the x chromosome - it does look like my mom passed down to me the x chromosome she got from her dad, and he got that from his mom (obviously), who had the surname Danley, which had the earlier spelling Dannelly. I am shooting from the hip on this, but I noticed one of my mom's x matches has the surname English listed. English was the maiden surname of my maternal grandfather's grandmother. So maybe she was the source of the x chromosome I received from my mother. Like I said, though, I am shooting from the hip on that and have not confirmed it.
Okay, I have at least confirmed that my x chromosome came via my maternal grandfather and thus from his mother, Missy Danley. I checked out an x match of my mom's who is definitely on my mother's maternal line. She appears as an autosomal match for me but not as an x match. That eliminates my maternal grandmother as the source of my x chromosome, ergo, I must have got the one my mom got from her dad.
David Mc
it does look like my mom passed down to me the x chromosome she got from her dad...
So this is possible? I had thought it was passed down in a straight matrilineal line (rookie that I am). Thinking about it, it makes sense I suppose, because "why not?" Our mothers carry two x chromosomes... pass one onto us... who is to say which one it will be?
I have to say, some FTDNA projects (at least) nudges you into thinking matrilineally when they ask you for your earliest known maternal ancestor.
If I recall correctly, a male child can inherit either the X from his maternal father or maternal mother. I know for a fact I received my X from my maternal mothers side, which is 100% southern Italian, because I have barely any X matches. My mom however has over 3000 X matches at 9cM. Which has to be my maternal grandfather, considering he's Slavic and Jewish.
When it comes to reproduction, the father's possibilities are either/or. That is, either he passes on a copy of his X chromosome -- without recombination; or he passes on a copy of his Y chromosome (also without recombination). This, of course, is what determines whether his child is a son or a daughter.
For mothers, though, there are actually three possibilities. Although any child she has will receive an X chromosome from her, whether the child is a son or a daughter, that child can receive: an X chromosome which containing DNA from both maternal grandparents; an X chromosome containing DNA from only the maternal grandfather; or an X chromosome containing DNA from only the maternal grandmother.
Which of these three things happens seems to be a matter of chance. The first scenario is the most common, but the second and third happen pretty regularly as well.
This happened in my own family. Out of the six offspring of my parents, three received an X chromosome from our father. These are my sisters, and on that X chromosome they are identical. The other three of us received a Y chromosome from our father: i.e., my brothers and me.
Now for reasons I'll get to below, I can tell that four of us received an X chromosome from our mother than contains DNA from both maternal grandparents, while two received an X chromosome from her than contains DNA from just one maternal grandparent. The evidence suggests that it's from our maternal grandfather.
When I compare genomes at 23andMe, I can see that none of the three brothers matches any other brother completely on the X chromosome. Therefore, no two of us received an identical recombination of our mother's X chromosomes.
With our sisters, this is more difficult to tell. "The New Experience" no longer distinguishes between full and half matching. Since they have the same father, my sisters have one identical X chromosome -- the one they inherited from our father. That means their genome comparison simply shows matching across the entire X chromosome.
("The Old Experience" did distinguish between full and half matching, so it was much easier to tell that my sisters don't match on all of their maternal X chromosome. But Gedmatch does still make this distinction, with one-to-one graphic comparisons.)
Fortunately, I can see that each brother matches each sister differently, which means that no two sisters can have identical maternal X chromosomes.
However, it's very important that I wrote, "no two sisters" As it turns out, my brother Bernie and my sister Kim match across the entire X chromosome. This has to be on their maternal copy of the X chromosome.
For this to have happened, the maternal X chromosome for each of them must either have had identical crossovers, or no crossovers. The latter seems much more likely; and if there were no crossovers, then all of the DNA is from the same grandparent. (Or conversely, if all of the DNA is from the same grandparent, then there were no crossovers and the chromosome is -- effectively -- unrecombined.)
Because Bernie and Kim have an identical maternal X chromosome, it also means that their matching with the other two brothers is identical. That is, the genome comparison between Bernie and me looks just like the comparison between Kim and me -- as far as just the X chromosome is concerned. And the same thing for Curt, of course.)
I match both of them for all of the X chromosome except for a comparatively small region surrounding the centromere. This region is only 19.28 cM in length.
Within the region where I don't match Bernie or Kim, the matches I share with DNA cousins have all proven to be on our maternal grandmother's side; outside the region -- on both arms -- the matches have all proven to be on our maternal grandfather's side.
A reasonable inference is that all of Bernie and Kim's maternal copy of the X chromosome is from our maternal grandfather.
Yeah, your mom has two x chromosomes: the one she got from her mother and the one she got from her father. I have been able to eliminate my maternal grandmother as the source of my own x chromosome because an x match my mom has on that same line is not an x match for me. That leaves my maternal grandfather as the source of my x chromosome, and of course he got his x chromosome (the only one he had to pass down) from his mother. His mother was a Danley, but her mother was an English. I spotted someone among my mom's x matches with the surname English in her list of ancestral surnames, so I am thinking my ancestor Sarah Lucinda English may be the most distant known source of my x chromosome. Can't really confirm that right now, though; it may not be right.
For mothers, though, there are actually three possibilities. Although any child she has will receive an X chromosome from her, whether the child is a son or a daughter, that child can receive: an X chromosome which containing DNA from both maternal grandparents; an X chromosome containing DNA from only the maternal grandfather; or an X chromosome containing DNA from only the maternal grandmother . . .
I was not aware of that. Thanks. Obviously that complicates matters.
What I mentioned earlier about my mother's x match with the surname English in her list of ancestral surnames turns out to be not so simple and straightforward, after all. My mother actually has a number of x matches with the surname English among their ancestral surnames, but in checking my own FF results, I find none of those people show up as x matches for me even though some of them show up as autosomal matches. So, something weird is going on, probably connected to what you were talking about.
The x could be more trouble than it's worth.
Exactly. Once you get past about four generations, my research is showing that the large matching segments are not IBD. People really do not know what they are looking at.
It can be, sometimes. It can also be a gold mine. It depends on what other family members you also have test results for. Obviously, the more the better.
The thing to remember about the X chromosome is that some matches can be truly ancient because of how often the X manages not to recombine. Everytime it's passed from the father to daughter, of course, but also sometimes even mother to daughter or mother to son -- just as it is with other chromosomes.
I have a niece whose paternal X chromosome is presumably identical to one that came from a great, great grandmother. Since the copy my brother got is traceable to our maternal grandfather -- and therefore to our maternal grandfather's mother -- that's the only one my niece could have received from my brother.
So this copy of my niece's X chromosome would have come from a woman born in the 1860s. It likely is a recombination of the her two X chromosomes -- but as you can see, it wouldn't have to be. And this niece has five children to whom she could have passed this X chromosome, in entire as part of a recombination.
Of course, it was just luck that my brother Bernie and sister Kim not only received an X chromosome entirely from one grandparent, but the same grandparent. It could have worked the other way. That would have meant they'd have 0 sharing on the X.
So this means you can't always tell, with half siblings, which side they're on just because there is no matching on the X chromosome. Usually the X will be recombined when recombination is possible. But just as autosomes are sometimes not recombined in a generation, sometimes the X chromosome isn't recombined, even though it could have been.
EDIT: I presume your English ancestors actually immigrated from Ireland, since that would seem like a odd name to acquire while living in England. (Sorry, but I kept help thinking of Johnny English.)
A 1st cousin 1R got a match on FTDNA recently and the X is huge compared to my 1st cousin 1R X comparison.
End Location
centiMorgans (cM)
# of Matching SNPs
Unfortunately both have unknown fathers so we are unable to help one another at this stage :(
I hope the OP will indulge what may be a bit of a digression, but I find the process by which recombination takes place to be immensely fascinating.
Along the way, the parent's 23 pairs of chromosomes end up first being doubled, so that for autosomes 1-22 there are now four of each. These are in the form of two pairs of "identical twins". For the X chromosome, a father will have two copies of the one he received from his mother; he'll also have two copies of the Y chromosome he got from his father.
These groups of four (or two, if there is both an X and a Y chromosome), are lined up together, and may end up exchanging parts -- I won't try to describe exactly how; but it sort of sounds like a wild party. But when recombination takes place, it can either be between two copies that are different (are from opposite parents), or two that are the same.
That means that, technically, each chromosome is always a recombination. Even the Y is a recombination of the doubled copies of the Y chromosome. But since the two copies were identical, the recombination is also identical -- except for the odd chance that some section manages to be spliced in backwards (a reversal).
Anyway, when this recombination has been completed, you end up with four new copies of chromosomes 1-22, and either four copies of the X chromosome (for a mother) or two of the X and two of the Y (for a father). Then these four sets are split up, with one complete set of chromosomes being wrapped up in a new nucleus, and split up into four new cells.
Usually, in a female only one of these will become a new ovum; the others will be what are called "polar bodies". But here's the thing. At the same time a copy of, say, the X chromosome that a woman inherited from her father was recombined with its identical twin, then the copy she received from her mother was also likely recombined with its identical twin. Any of the four new cells might become an ovum, so there are two chances the X in that ovum with be from grandpa only; and two chances it will be from grandma only.
If you're interested, there's information on the process -- called meiosis -- all over the internet. (Some of it is even correct.) For example, there's https://en.wikipedia.org/wiki/Meiosis.
Thanks, all, for your responses.
Unfortunately both have unknown fathers so we are unable to help one another at this stage.
Yeah, 55 cM is over a fourth of the entire chromosome. (That's 195.93 cM, as calculated at FTDNA. http://isogg.org/wiki/CentiMorgan)
Is this 1st cousin once removed perhaps female? [You already said the two have unknown fathers, so I'm assuming the relationship is on their fathers' sides.] In that case both 1st cousin and 1st cousin 1R would be identical* -- as far as just the X chromosome is concerned, that is.
My largest X-chromosome match with anyone who isn't my daughter or one of my siblings, is with a 3rd cousin. We actually share two segments that are reasonably large: one is 33.54 cM, and the other is 24.49 cM. Together that's actually 58.03 cM.
However, the 3rd cousin and I are both male, so our matching on the X chromosome may be just as large as the matches would be between our mothers -- who would have been 2nd cousins.
*Well, not identical. Obviously, the daughter would have two X chromosomes and her father would only have one. What I meant to say was that her paternal X chromosome would be identical to his maternal (and only) X chromosome.
This person is related to my cousin 1R but does not share any DNA with myself or my paternal 1st cousin. BTW this match has more on the X than my cousin and our cousin 1R. Actually my dad's cousin!
FTDNA predict 3rd cousin. The match may well be on their maternal side but the only living relative is not keen on testing :(
[QUOTE=geebee;211815]Is this 1st cousin once removed perhaps female? QUOTE]
To illustrate the idea that the source of an X chromosome segment can appear closer than is actually the case, I worked out X paths leading to a common ancestor of both my "3rd cousin" and me. (It turns out that we're related in a couple of ways, but the closest seems to actually be 4th cousins once removed.)
For me, the path is
Rachael Jones (1)> John "Jailor" Sizemore (2)> Mary Ann "Polly" Sizemore (3)> Hannah Louise Muncy (4)> my grandfather (5)> my mother (6)> me
This represents six transmissions of the X chromosome, but only four times where two X chromosomes could recombine. In the two father-to-daughter transmissions, recombination wasn't possible. So while Rachael is my 4th great grandmother, as far as the X-chromosome is concerned she might as well be my 2nd great grandmother.
For my cousin, the path is
Rachael Jones (1)> William D. "Willis" Sizemore (2)> Rachel Sizemore (3)> Felix Sizemore (4)> my cousin's mother (5)> my cousin
This represents five times that the X chromosome was transmitted, but only three times in which recombination could take place. So Rachael is my cousin's 3rd great grandmother, for for the X she is effectively his great grandmother.
I definitely have to say that knowing the possible paths of the X chromosome helped a lot in this case; but you do have to have something to go on. Unfortunately, DNA can't entirely uncovering some sort of paper trail. But on the upside, it can allow you to see where the paper trail may not be making sense -- although that's true of autosomal DNA, and not just for the sex chromosomes. (It's just that the X chromosome can greatly reduces the number of possible paths.)