Genetic Chimeras

[vampyre_smiles]

If the DNA in said chimera is from a male and a female sibling who fused, are they technically considered intersex? If so, is it automatically or a "Yes, but/if..." situation?

I was curious about this for a while and thought I'd see if anyone knew.

[Julie Herds Cats]

Chimerism is an Intersex condition if the sex chromosomes are different, or if the differences are significant. 47/XY,XO is Mixed Gonadal Disgenesis, but 47/XX,XO might not be anything.

Chimerism isn't always uniformly distributed, so the extent to which intersex physiology might be present varies.

[Ryles]

I saw something about a kid who was born half male, half female- half black, half white. Straight up the middle, you could see the line on their stomach. I think they were lucky and there wasn't anything on their face, because people can be pretty awful. I think they would qualify as intersexed.

I'm not sure how rare that is. From what I've seen of chimeras, it seems like often you don't know until you get a paternity test and the kid isn't the mother's. So unless the ovaries don't match the body, or it causes a visible difference, you might never know- it's not like people are going to sit there and test every different tissue in your body just to make sure you're chimera.

[vampyre_smiles]

it's not like people are going to sit there and test every different tissue in your body just to make sure you're chimera.

I was mostly interested because I know someone who is a chimera and it was found out pretty early in life, because he and his twin sister were supposed to be triplets, one boy and two girls.

I'm guessing the answer is in the "Yes, if..." category.

[Shadow Dragon]

Well if one set of dna is male and the other is female, then yes, that chimera would be intersex to some degree. Obviously just how intersex they are will vary greatly from person to person.

[Julie Herds Cats]

Well if one set of dna is male and the other is female, then yes, that chimera would be intersex to some degree. Obviously just how intersex they are will vary greatly from person to person.

It's not just "one set", it's also the ratio. Chimerism isn't always 50/50. I think the lowest ratio is around 1:64. After too many divisions, fusion isn't possible, as I understand it.

(And I'd be incredibly surprised (as in "Not believe at all") that anyone could be divided straight up the middle, since that's not at all how early fetal development works)

[Ryles]

(And I'd be incredibly surprised (as in "Not believe at all") that anyone could be divided straight up the middle, since that's not at all how early fetal development works)

http://www.youtube.com/watch?v=wtZgxsAkA3s I think it's about 40 seconds in.

I'd suggest trying to track down the parents' number so that you can call them up and let them know that you don't believe their child could exist.

And, before you try pointing this out, I did not say that the child was 50% this DNA, 50% that DNA- I said that their skintone was split down the middle, but wasn't on their face (I didn't comment on the extremities because I didn't see it), which is the case. I believe their genitalia also was, I know that it was half male and half female, but it's not like they showed a diagram.

[Shadow Dragon]

(And I'd be incredibly surprised (as in "Not believe at all") that anyone could be divided straight up the middle, since that's not at all how early fetal development works)

Look it up yourself, then. It was on a TV special about chimeraism- 2 cases of issues with paternity tests, one with that kid.

Yeah, I've seen that special, and althouth it doesn't happen throughout the whole body, that are sometimes parts of the body that end up seemingly divided in half.

In one case, a baby's stomach and chest area was pretty much divided in half horizantaly, where it's skin shade on the right was much darker than it's skin on the left.

In another one, it was literally half male and half female. It had a penis and one testicul, as well as half a uterus and one ovary. I'm pretty sure they did surgury on this kid to remove the female bits, due to the fact that it could still reproduce as a male.

[Julie Herds Cats]

Yeah, I've seen that special, and althouth it doesn't happen throughout the whole body, that are sometimes parts of the body that end up seemingly divided in half.

"Seemingly" is believable.

Calico cats are chimeras as well -- the "White" versus "Color" gene and "Orange" versus "Brown/Black" gene are sex-linked. That's why male Calicos are sterile -- they are all 47,XXY.

[not_quite_pie]

Yeah, I've seen that special, and althouth it doesn't happen throughout the whole body, that are sometimes parts of the body that end up seemingly divided in half.

"Seemingly" is believable.

Calico cats are chimeras as well -- the "White" versus "Color" gene and "Orange" versus "Brown/Black" gene are sex-linked. That's why male Calicos are sterile -- they are all 47,XXY.

Calico cats are not chimeras. The colour patches are the result of X-inactivation (being, as you correctly stated, due to X-linked genes). X inactivation is a completely normal phenomenon in mammalian females and XXY individuals; one X gene is inactivated (for the most part) during foetal development. The X which is inactivated is random, resulting in colour patches in the cat's fur as the orange and black/brown genes are expressed in different areas of the skin.