There are various early entrance (college) programs (eep) scattered throughout the US, though many with restrictions. I know a teen at BU Academy who has been able to take courses at BU since they have an agreement with the school. However, a BU academy student has to either have completed the math curriculum at BU Academy or taken the math test to take math courses at BU (somewhat like a dual enrollment); and even then, there are age restrictions. I think 14 yrs old is the earliest that BU Academy students can take math courses at BU.

What information or details are you looking for? The different approaches or what to do with a child in that situation? Or are you looking for examples? If so, here's a wikipedia list of child prodigies (https://en.wikipedia.org/wiki/List_of_child_prodigies) which you could easily verify the details on these children and what approach they took.

Also, though, there are number of people who are not listed on this wikipedia page and who have gone through an eep or something similar. Ronan Farrow (Mia Farrow's and possibly Frank Sinatra's biological son, though formerly Woody Allen's) comes to mind. He went to Bard College at Simon's Rock at 11. And while Mia and Woody certainly had the money for Ronan to attend Simon's Rock or earlier with tutors, they still would have had to decide what to do with Ronan and how to go about it (and without the publicity during the midst of the Woody Allen scandal). At the end of the day, Ronan would still have had to be social/emotional ready for Simon's Rock as well as the academics. He commuted from his CT home (by limo, of course!) so that helped to smooth his transition.

I think you'll notice a mixture of approaches though. Some people seem to follow a more formal, traditional school approach. Others, however, take a more informal, unconventional approach. I'm not sure one is better than the other. I think a lot of it depends on the child, motivation level, drive, environment, etc.

You'll find opposites. Marvin Hamlisch went to Juillard at 6.5 yrs old, but Joey Alexander (who was recently featured on 60 Minutes) hasn't had much formal musical training and has been playing with Wynton Marsalis. With math, there's Terrance Tao at UCLA who had a more formal math training and was taking university courses at 9 and participating in math olympiads early on. Erik Demaine, by comparison, was homeschooled and lived/traveled around the country in a camper with his father until 12.

Not sure if this helpful or not. Or what information you're looking for...