[ronaldx]

Apologies for editing my point above.

Chimerism is well-studied because it's biologically interesting, but most social/medical professionals are not expected to come across human chimerism in their whole career.

Chimerism not often documented in humans and the other possibilities (e.g. surrogacy scam) are hugely more probable explanations.

[Locke1689]

I think the parent's point is that, while rare in practice, well-qualified physicians should easily identify the unusual situation and propose the alternate hypothesis.

As an aside, this fact was of great annoyance to me when I was younger, as the child of two pathologists trying to watch the tv show House. If you're not familiar, it's a medical mystery show with a genius misanthrope doctor named House who diagnoses people with extremely rare diseases, almost killing them in the process.

It was a regular occurrence for one of my parents to walk through the room while I was watching the show, in the first 5 minutes, and throw out, "they obviously have x (vasculitis, chimerism, etc.)," thus ruining the rest of the episode for me. Of course, they never actually watched the show, since from their perspective it was just an incompetent medical team torturing some patient.

[tzs]

A site with a medical review by a doctor of every "House" episode: http://www.politedissent.com/house_pd.html

[ronaldx]

That your parents and the parent commenter react in this way ("it's obvious") is by design of the author of the piece and the author of House.

I can watch an episode of House and anticipate "they obviously have lupus", which makes me feel intelligent and satisfied even though I can see they are planting obvious clues from the very start which a diagnostician would be mind-numbingly stupid to ignore.

The same with the headline of this article. It's designed that way. In reality, you don't get to read the headline or watch the episode before making a clinical decision.

Regarding House: in mid-series episodes, I believe they occasionally subvert this by planting clues for the wrong thing. At least, I enjoyed being wrong in those episodes.