I know you were wondering how I was going to top a shirtless Mark Twain.
I give you, “Report of Fertility in a Woman with a Predominantly 46,XY Karyotype.” In short, everything you were taught in high school biology just got more wronger.
More wronger. I was going to fix that, but, if high school biology is wrong, maybe high school grammar is, too.
Tiny Cat Pants 
“The Desert hedgehog gene…”
Really???
I just…
Desert hedgehog gene? Is a thing. I read that whole piece and then wondered if it was a catfish. (Clinical catfish.)
We definitely need Rachel to interpret. But I think what they’re saying is that this woman has a really strange form of mosaic um, whatever it’s called, where your body doesn’t have the same DNA throughout. I don’t think chimerism is the right term, but something like that. So, she is mostly XY but her reproductive tract may just be X?
Which seems plausible to me. But I’m no scientist.
As a lurker medical librarian, I thought I might comment. Chimerism is when multiple zygotes are involved – two fertilized eggs or early embryos fused together. Mosaicism is when multiple genotypes develop from a single fertilized egg because of genetic recombination or mutation during development.
But that’s not quite what’s going on here. Although the mother’s skin showed mosaicism (a mix of XX and XY), the genotype of the mother’s ovaries was overwhelmingly 46,XY. According to the article, “ovarian cells were predominately 46,XY; the small percentage of X (5.9%) out of 1000 cells counted in the gonad might be due to artifact or technical error” and “most cytogeneticists agree that 5% does not indicate mosaicism” (that is, 5% is not enough to be considered true mosaicism).
So – the mother’s XY ovarian cells created normal, fully-functioning, fertile ovaries. The researchers said basically, huh, no one has ever seen that before, but that might be because we don’t usually test people to see if something is different about their fully-functional ovaries. It might happen all the time – we just don’t know. Amazing.
I have more than one medical librarian who reads me?! That makes my day. And thanks for explaining. That is both more awesome than I could have imagined and more complicated than I could make sense of.
So, does this mean it’s possible that there are guys with XX testicle cells who have kids so no one has noticed?
I just love this. Life–it’s so freaky.
I know two other medical librarians who read you at least occasionally. :) (assuming Layla isn’t a pseudonym for one of them)
I agree that it might be something that’s way more common than we think, and that is very cool. I don’t see why the same couldn’t be true of your testicle example in the last comment, since we know so little right now.
Nope, not a pseudonym (although I did briefly meet you on the escalator at MLA in Seattle – I was very excited to find myself next to a celebrity). And I’m pretty sure I came to Tiny Cat Pants through your blog.