Others will probably have more detailed/accurate info, but my suggestion would be to retest using the WISC-IV at age 6, with extended norms that are claimed to test up to 210.

WISC–IV Extended Norms

There is also an interesting discussion here, though it could be organized better: What is Highly Gifted? Exceptionally Gifted? Profoundly Gifted?

Last edited by Cranberry; 02/07/17 10:58 AM.