This question already has an answer here:
Another request to help identify a book read in my youth.
Elements I think I remember:
- Certain kids can see rings or portals floating in the air.
- This is apparently made possible by a small extra ring of DNA unique to each of these kids' cells (I don't remember the term plasmid specifically used).
- These portals are invisible to most people but show up as different colors and have different qualities assisting travel.
- The protagonist is a girl who can see more unusual kinds of portals than other kids, though most of the other portals don't seem to have a purpose or can't be entered.
- I think the kids are under control of some government organization or scientists or something, but am unsure.
- Probably had more a feel of sci-fi than fantasy, but I don't remember a clear scientific rationale for the phenomena involved.
Unfortunately, other than maybe exploiting something unique about her own powers, I don't remember much about the plot. Google isn't much help since there are a lot of books about portals and rings.
I probably read this in the late 1980s or early 1990s, but it may well date a decade or more earlier. I feel like this was middle grade or young adult fiction but somehow got housed in the library with adult fiction for reasons unknown.
Any help in figuring it out is appreciated.