Genetic Chimeras

human genetics

Has everyone heard of Chimera?

The mythical creature who terrorised parts of Ancient Greece. The head of a lion, body of a goat and tail of a dragon/snake.

Well, some of you may not of heard of the Human Chimera.

Some peoples blood contains cells from a brother or sister, others are two individuals rolled into one. Yet more carry a distinct mutation in only parts of there bodies.

This arcticle is from the News Features Section of the Journal Nature.

Eight years ago in Britain, a boy was born who was genetically 2 difrent people. He formed when two eggs fertilized by two diffrent sperm, fused into one embryo inside his mothers womb.

He was an unremarkable baby, but as a toddler doctors discovered that he was a hermaphrodite - what was originally diagnosed as an undescended testis turned out to be an ovary, a fallopian tube and part of a uterus. Further investigation revealed that some parts of his body were genetically female but the rest, which contained a different combination of his parents' genes, was male1.

The boy, who was otherwise healthy, is one of only a handful of known true human chimaeras - people carrying tissues that originated in two separate embryos. More common are mosaics, who have patches of tissue that differ genetically from the rest of their body, thanks to a mutation or chromosomal anomaly that arose early in embryological development
The frequencies of chimaerism and mosaicism are unknown, but doctors might benefit from a better understanding of both conditions. In recent years, tantalizing hints have emerged that pockets of genetically mismatched cells may contribute to conditions as common as infertility, autism and Alzheimer's disease. "I think mosaicism has been neglected as an underlying cause of disease," says Huntington Potter, who works on the genetics of Alzheimer's at the University of South Florida in Tampa.
And if chimaeras and mosaics are more common than we realize, they will complicate future efforts to tailor drug treatments to people's individual genetic constitutions. Two genetically different tissues in one body might produce an unpredictable response to a drug, speculates Roland Wolf, who studies pharmacogenetics at the University of Dundee, UK. "It's completely unknown," he says.

The twin within

Human chimaerism first came to light with the advent of blood typing - some people, it emerged, have more than one blood group. Most are 'blood chimaeras', non-identical twins who shared a blood supply in the womb. Those who were not born a twin are thought to be pumping around the remnants of a sibling that died early in gestation and was spontaneously aborted. One British woman, for instance, was unaware that she once had a twin until routine blood tests during her pregnancy in the early 1980s revealed a population of chromosomally male blood cells2.
Twin embryos often share a blood supply in the placenta, allowing blood stem cells to pass from one embryo and settle in the bone marrow of the other, seeding a lasting source of blood. As a result, as many as 8% of non-identical twin pairs have chimaeric blood3. And given that most multiple conceptions that result in live births involve the loss of one twin early in pregnancy4, there may also be significant numbers of blood chimaeras among single births.



www.nature.com...

Related links

1: stuff of mosaicism www.medgen.ubc.ca...

2: stuff on Blaschko's lines www.medical-acupuncture.co.uk...



More info when i find it

Also found these related links that involve Chimerism and Mosaicism

I know this is a weird subject but its fascinating to people interested in medical science and all...also, what if u knew someone who had these genetics, wouldnt u like to know a bit more about it?

related links

organtx.org... ~ detailed info using stem cell, mosaicism and donor kidneys to say a woman.


www.gender.org.uk... ~ details three diffrent types of Chimerism

encyclopedia.thefreedictionary.com... ~ encyclopedia explaining Chimerism.

www.google.com... ~ Google search i used.

I know many people dont understand this...hell i dont either in some bits but it kinda links the whole Genetics/StemCell and Cancer Research together so i thought i would post it ok

any comments...or did i just bore the crap out u?

I, for one, am reading through the links, but it is a lots for my poor brain to digest. "Of all the things I've lost, I miss my mind the most."

Seriously, the only readng I've done on chimeras involve the manipulation of Mycoplasma to create weaponized pathogens. The links you have provided are interesting, especially the pigment disorder.

I will permit a glimpse into my inner-geekiness by mentioning that my first reaction to that images was that someone was breeding camouflage into the species, a la the Dagwood character on "Seaquest DSV"

LOL

I KNEW someone would post that!!!

*yes...i liked Seaquest myself*

I just think the whole subject is fascinating, the ability for ur body to hold 2sets of DNA interlinked during embryotic growth..wow!

You can see where they got the idea from now cant you, and i wouldnt be suprised if they did start experiments for camolflage, almost like cross insemination a goat and injecting Chameloeon DNA into it.

Anway...more info as soon as i stop confusing myself

Thanks for the great read Gryffen and your very good detailed explanation of what the 'Human Chimera' is.

I had heard of the mytholigal creature called the chimera.

I guess the phrase 'get in touch with your feminime side' is a possibilty for some.

Learn something new everyday

Rynaldo

Good stuff Gryff, though I'm admittedly still digesting some of it.

Just some added information found on the same type of topic, but dealing with the animal kingdom as well.

*someone at the local uni is doing a theory on this and i got nosy so this is how this started off....if yer gettin picky..dont pay attnetion to his ok...just some medical stuff incase ur interested.

Related Links

arbl.cvmbs.colostate.edu... ~ just stuff about animal genetic chimeras.

www.mmhs.com... ~ just stuff on medical genetics.

www.mygnp.com...:content:ency:article:001317 ~ contains definitions, causes and risks.

A person who is a 'genetic mosaic' has cells from two or more different genetic constitutions. This usually is found as a variation in the number of chromosomes in the body's cells. Normally, all body cells would have the same number of chromosomes (46). But in mosaicism, some cells may have 47 chromosomes (such as extra chromosome 21 or X chromosome in some, but not all cells).

www.ucalgary.ca... ~ detail background

hope this dont bore u all

Now I will expose my inner geekiness as well. Recently there was an episode of CSI that delt with this issue which got me interested in the subject. A man was raping women without blindfolds or anything. He wanted to be seen, they put him in a line up and he was of course picked by the woman who he had raped. They tested his DNA and it didnt match the rape kit so they let him go. The DNA was close but no match so they interviewed his brothers and it was none of them either. THen the lead CSI, Grissom saw the lines on the guys back like in that picture and he took a blood sample which mathced the rape kit. Turned out his sperm didnt have the same DNA as his blood and skin.

Looks like I may be one... Going to try and find out through some testing. I've had two official blood types throughout childhood, so this may just be the answer....

I'm a hell of a freak huh? First a SLIDER, and now this...

At least this would explain a lot....

[edit on 20-9-2004 by Gazrok]

great article on this...

www.deccanherald.com...

Originally posted by zsandmann
Now I will expose my inner geekiness as well. Recently there was an episode of CSI that delt with this issue which got me interested in the subject.

I was ready to reply with the CSI details, myself. Am I the only one who sees a show or movie or reads an article that I just *know* will pop up on ATS? Discover magazine is a great outline for the medical and scientific threads that pop up. It's fun to try and figure out where the ideas for topics came from...

Chimeras are interesting though, and the show made me think a lot about the possibilities for these people and if it was possible at all. How often does it naturally occur? Is it possible to create a chimera through in-utero manipulation? How does the body regulate protien synthesis if there is different DNA in different cells? Do the hormones produced by some DNA not effect other cells? Sterile? Always survivable or just some chimera individuals with only specific differences? Medical treatments different? Hmmm.. now that CSI introduced it, Discovery Health Channel needs to pick up the ball and run with it before Sci-Fi Channel beats them to it, or Dateline NBC has a Chimera Sex story before sweeps

If it turns out I am one, I'll definitely be delving more deeply into it. So far, seems they don't know how rare it is, as its usually only found when doing DNA tests to determine donor compatibility, etc. and even then, they've got to get lucky enough to get the DNA from a place that differs from the norm.

In the cursory research I've done, it seems that animal chimeras are genetically created all the time, for testing purposes. It seems if I am one, then the other embryo that I absorbed was also male. They've found that true hermaphrodites are caused when the two embryos are different sexes. That could lead to sterility, but not so in my case, as I know I am not. Survivability doesn't seem to be an issue, as no adverse affects, other than perhaps genetic susceptability odds. All good questions though, and something for me to find out, if I am one.

Originally posted by Gazrok
They've found that true hermaphrodites are caused when the two embryos are different sexes. That could lead to sterility, but not so in my case, as I know I am not.

Eh? Where'd you read this? Aren't they caused by the hormone baths the fetus receives during sexual maturation that dictates the type of gonadal tissue that would be formed? That and people with XXY chromosomes that have genetic material for both male or female, but unrelated to twinning?

Sounds like a good plot for SouthPark with the genitals of a malformed conjoined twin speaking to the world via Cartman's crotch.

WOW..Gaz...thats great news and also a probable relief to u.

I have a friend in Halifax who has been tested for it...the other embryo was male and she has 2 sets of DNA.

If and when i find more info on this ill put it down here so its available to everyone...which is better.

Stay safe
gryff

Gazrok re your closed thread on "I'm a Monster...":

For blood type specific info, check out this site: anthro.palomar.edu...

A small number of people have two different ABO blood types.� They are not simply AB codominant.� Apparently, most of these blood chimera individuals shared a blood supply with their non-identical twin before birth.� In some cases, people are unaware that they had a twin because he or she died early in gestation and was spontaneously aborted.� As many as 8% of non-identical twins may have chimeric blood.� Some people are microchimeric--they have a small amount of blood of a different type in their system that has persisted from a blood transfusion or passed across the placental barrier from their mother before birth.� Likewise, fetal blood can pass into a mother's system.� This fact has led some researchers to suggest that the significantly higher frequency of autoimmune disorders in women is a result of the presence of foreign white blood cells that had come from their unborn children during pregnancy.

Normally, if you mix two different blood types together they clot and clump and kill you. Not in these cases, though. What it DOESN'T mention is having two different types of DNA, which was more of the jist of the CSI show on genetic chimera.

So, you're not a monster, just a freak

Just MORE of a freak, hehe.... Oddly enough, one of the types was AB (can't remember positive or negative), and other was O (again, not sure on the positive/negative)....

I read about a case a while back where a Woman(I think She lived in NY)who was a Chimera,Her two children didn't match Her genetically or by blood type.