The rule is that the minor children of political figures are always off-limits. That applied to the Obama girls, and it now applies to Barron Trump.

The problem is that on the internet, EVERYONE is a medical/mental health/psychology expert. If you want proof of that, just look up how many anti-vaccination groups exist on Facebook, where everyone’s confirmation bias is reinforced by an echo chamber with no medical credentials at all.

So one guy on YouTube made a video, after seeing people comment about Barron Trump’s behavior, that collected all the “evidence” that Barron may be on the autism spectrum. (UPDATE 3:30 PM EST: the video in question has now been removed by the user, presumably because of the legal threat detailed below.)
https://www.youtube.com/watch?v=yZAd5Pu9iw4
Which then got tweeted out by someone who has NO love for Donald Trump whatsoever – Rosie O’Donnell.

Rosie has since deleted the tweet after getting an enormous pushback from decent human beings on Twitter and elsewhere, but the insinuation was officially now in the mainstream.

And now Melania Trump has had enough.

Melania Trump has hired a famous lawyer who is now threatening a lawsuit over a video suggesting her 10-year-old son, Barron, is autistic, and the letter calls out Rosie O’Donnell as a bully.
According to the letter, obtained by TMZ, the YouTube video falsely insinuates Barron is autistic. The letter, and our sources familiar with the situation, say Barron absolutely is not autistic.