We've had at least a couple of members whose DS is mathematically talented/gifted and their overall IQ did not match their math achievement.

I also read a blog post by a mother of a talented young violinist who was rather puzzled by the lower-than-expecred results.

My speculation is that some children can be very talented in one or two areas but not necessarily perform well on standard IQ tests. IMO, that doesn't make them less gifted or talented in their areas of strength.