I'm a Wikipedian, and I'm fully with you in not taking Wikipedia as authoritative about much of anything, because I have seen how the sausage is made at Wikipedia. That said, after a Google search, I saw that the two articles I linked to showed that many medical syndromes are named without a possessive ending on the personal name associated with the syndrome, including Down syndrome, and that was the immediate point at issue.

By the way, I try to light a candle as well as curse the darkness at Wikipedia, by gathering lists of good sources for all the Wikipedians to use,

https://en.wikipedia.org/wiki/User:WeijiBaikeBianji/Intellig...

https://en.wikipedia.org/wiki/User:WeijiBaikeBianji/Anthropo...

and by updating articles that have long been tagged as needing improvement.

https://en.wikipedia.org/wiki/IQ_classification

I wish that Wikipedia were much better, but the current way to make it better is for people to roll up their sleeves and do something about making it better.